diff --git a/src/proto_alpha/lib_delegate/block_forge.ml b/src/proto_alpha/lib_delegate/block_forge.ml
index 102fd897253bb90d6020639e8064e6bd325d0c0b..ed71e94dcb9a0b64692fd406b214efa3eff0fa55 100644
--- a/src/proto_alpha/lib_delegate/block_forge.ml
+++ b/src/proto_alpha/lib_delegate/block_forge.ml
@@ -445,6 +445,7 @@ let aggregate_attestations eligible_attestations =
       with
       | Some signature ->
           let contents =
+            let committee = Operation.tmp_of_old_committee committee in
             Single (Attestations_aggregate {consensus_content; committee})
           in
           let protocol_data = {contents; signature = Some (Bls signature)} in
@@ -550,7 +551,9 @@ let aggregate_attestations_on_reproposal consensus_operations =
       (* The proposal already contains an aggregate.
          We must incorporate additional attestations *)
       (* Build the set of aggregated slots for a logarithmic presence lookup *)
-      let aggregated_slots = SlotSet.of_list committee in
+      let aggregated_slots =
+        SlotSet.of_list (Operation.committee_slots committee)
+      in
       (* Gather slots and signatures incorporating fresh attestations. *)
       let committee, signatures =
         List.fold_left
@@ -561,7 +564,7 @@ let aggregate_attestations_on_reproposal consensus_operations =
               when not (SlotSet.mem consensus_content.slot aggregated_slots) ->
                 (consensus_content.slot :: slots, signature :: signatures)
             | _ -> acc)
-          (committee, [signature])
+          (Operation.tmp_to_old_committee committee, [signature])
           eligible_attestations
       in
       (* We disable the subgroup check for better performance, as operations
@@ -571,6 +574,7 @@ let aggregate_attestations_on_reproposal consensus_operations =
       with
       | Some signature ->
           let contents =
+            let committee = Operation.tmp_of_old_committee committee in
             Single (Attestations_aggregate {consensus_content; committee})
           in
           let protocol_data = {contents; signature = Some (Bls signature)} in
diff --git a/src/proto_alpha/lib_plugin/mempool.ml b/src/proto_alpha/lib_plugin/mempool.ml
index a67d84292e08be12bb535ebffec08d52dd6c4bfb..84cf49212ef7dce80436b8d49dd0dab1a48d76a9 100644
--- a/src/proto_alpha/lib_plugin/mempool.ml
+++ b/src/proto_alpha/lib_plugin/mempool.ml
@@ -799,54 +799,50 @@ let get_context context ~(head : Tezos_base.Block_header.shell_header) =
   in
   return ctxt
 
+let sources_from_level_and_slot ctxt level slot =
+  let open Lwt_syntax in
+  let* slot_owner = Stake_distribution.slot_owner ctxt level slot in
+  match slot_owner with
+  | Ok
+      ( _ctxt,
+        {
+          delegate;
+          consensus_pkh;
+          consensus_pk = _;
+          companion_pkh = _;
+          companion_pk = _;
+        } ) ->
+      return [delegate; consensus_pkh]
+  | Error _ -> return_nil
+
+let sources_from_aggregate ctxt
+    (consensus_content : consensus_aggregate_content) slots =
+  let open Lwt_syntax in
+  let level = Level.from_raw ctxt consensus_content.level in
+  Lwt_list.fold_left_s
+    (fun acc slot ->
+      let* sources = sources_from_level_and_slot ctxt level slot in
+      return (sources @ acc))
+    []
+    slots
+
 let sources_from_operation ctxt
     ({shell = _; protocol_data = Operation_data {contents; _}} : Main.operation)
     =
   let open Lwt_syntax in
-  let map_pkh_env = List.map Tezos_crypto.Signature.Of_V2.public_key_hash in
   match contents with
   | Single (Failing_noop _) -> return_nil
   | Single (Preattestation consensus_content)
-  | Single (Attestation {consensus_content; dal_content = _}) -> (
+  | Single (Attestation {consensus_content; dal_content = _}) ->
       let level = Level.from_raw ctxt consensus_content.level in
-      let* slot_owner =
-        Stake_distribution.slot_owner ctxt level consensus_content.slot
-      in
-      match slot_owner with
-      | Ok
-          ( _ctxt,
-            {
-              delegate;
-              consensus_pkh;
-              consensus_pk = _;
-              companion_pkh = _;
-              companion_pk = _;
-            } ) ->
-          return @@ map_pkh_env [delegate; consensus_pkh]
-      | Error _ -> return_nil)
-  | Single (Preattestations_aggregate {consensus_content; committee})
+      sources_from_level_and_slot ctxt level consensus_content.slot
+  | Single (Preattestations_aggregate {consensus_content; committee}) ->
+      sources_from_aggregate ctxt consensus_content committee
   | Single (Attestations_aggregate {consensus_content; committee}) ->
-      let level = Level.from_raw ctxt consensus_content.level in
-      let* sources =
-        Lwt_list.fold_left_s
-          (fun acc slot ->
-            let* slot_owner = Stake_distribution.slot_owner ctxt level slot in
-            match slot_owner with
-            | Ok
-                ( _ctxt,
-                  {
-                    delegate;
-                    consensus_pkh;
-                    consensus_pk = _;
-                    companion_pkh = _;
-                    companion_pk = _;
-                  } ) ->
-                return (delegate :: consensus_pkh :: acc)
-            | Error _ -> return acc)
-          []
-          committee
-      in
-      return @@ map_pkh_env sources
+      sources_from_aggregate
+        ctxt
+        consensus_content
+        (Operation.committee_slots committee)
   | Single (Seed_nonce_revelation _)
   | Single (Double_preattestation_evidence _)
   | Single (Double_attestation_evidence _)
@@ -856,10 +852,10 @@ let sources_from_operation ctxt
   | Single (Vdf_revelation _) ->
       return_nil
   | Single (Proposals {source; _}) | Single (Ballot {source; _}) ->
-      return @@ map_pkh_env [source]
-  | Single (Drain_delegate {delegate; _}) -> return @@ map_pkh_env [delegate]
-  | Single (Manager_operation {source; _}) -> return @@ map_pkh_env [source]
-  | Cons (Manager_operation {source; _}, _) -> return @@ map_pkh_env [source]
+      return [source]
+  | Single (Drain_delegate {delegate; _}) -> return [delegate]
+  | Single (Manager_operation {source; _}) -> return [source]
+  | Cons (Manager_operation {source; _}, _) -> return [source]
 
 module Internal_for_tests = struct
   let default_config_with_clock_drift clock_drift =
diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index 4a43e54b22afd463467dd2e30ad6b25c4a1015f4..20dbcaf28d107fe4938d2b9a42f4b9f4bdb5a48a 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -4722,7 +4722,7 @@ and _ contents =
       -> Kind.preattestations_aggregate contents
   | Attestations_aggregate : {
       consensus_content : consensus_aggregate_content;
-      committee : Slot.t list;
+      committee : (Slot.t * dal_content option) list;
     }
       -> Kind.attestations_aggregate contents
   | Seed_nonce_revelation : {
@@ -5154,6 +5154,13 @@ module Operation : sig
   val of_list : packed_contents list -> packed_contents_list tzresult
 
   val to_list : packed_contents_list -> packed_contents list
+
+  (** See {!Operation_repr.committee_slots}. *)
+  val committee_slots : (Slot.t * dal_content option) list -> Slot.t list
+
+  val tmp_to_old_committee : (Slot.t * dal_content option) list -> Slot.t list
+
+  val tmp_of_old_committee : Slot.t list -> (Slot.t * dal_content option) list
 end
 
 (** This module re-exports definitions from {!Stake_storage},
diff --git a/src/proto_alpha/lib_protocol/apply.ml b/src/proto_alpha/lib_protocol/apply.ml
index f6f304c13a1b001b9cdf9c685a7e5a9d4d429a90..cee57d76ae1c77a0e3ad429ee0033bfe10787429 100644
--- a/src/proto_alpha/lib_protocol/apply.ml
+++ b/src/proto_alpha/lib_protocol/apply.ml
@@ -2558,7 +2558,10 @@ let apply_contents_list (type kind) ctxt chain_id (mode : mode)
           (Constants.aggregate_attestation ctxt)
           Validate_errors.Consensus.(Aggregate_disabled)
       in
-      record_attestations_aggregate ctxt mode committee
+      record_attestations_aggregate
+        ctxt
+        mode
+        (Operation.tmp_to_old_committee committee)
   | Single (Seed_nonce_revelation {level; nonce}) ->
       let level = Level.from_raw ctxt level in
       let* ctxt = Nonce.reveal ctxt level nonce in
diff --git a/src/proto_alpha/lib_protocol/operation_repr.ml b/src/proto_alpha/lib_protocol/operation_repr.ml
index bff7fd97cd65f2267a6afdf4e9eef2b3dba16ce2..ca9d76c3e8777bd7f92cc562522ca597b1859e8e 100644
--- a/src/proto_alpha/lib_protocol/operation_repr.ml
+++ b/src/proto_alpha/lib_protocol/operation_repr.ml
@@ -296,7 +296,7 @@ and _ contents =
       -> Kind.preattestations_aggregate contents
   | Attestations_aggregate : {
       consensus_content : consensus_aggregate_content;
-      committee : Slot_repr.t list;
+      committee : (Slot_repr.t * dal_content option) list;
     }
       -> Kind.attestations_aggregate contents
   | Seed_nonce_revelation : {
@@ -551,6 +551,13 @@ let of_list l =
   | Ok contents -> Ok contents
   | Error s -> Result_syntax.tzfail @@ Contents_list_error s
 
+let committee_slots committee = List.map fst committee
+
+let tmp_to_old_committee committee = List.map fst committee
+
+let tmp_of_old_committee committee =
+  List.map (fun slot -> (slot, None)) committee
+
 let tx_rollup_operation_tag_offset = 150
 
 let tx_rollup_operation_origination_tag = tx_rollup_operation_tag_offset + 0
@@ -1257,9 +1264,13 @@ module Encoding = struct
           | Contents (Attestations_aggregate _ as op) -> Some op | _ -> None);
         proj =
           (fun (Attestations_aggregate {consensus_content; committee}) ->
+            (* TODO: https://gitlab.com/tezos/tezos/-/issues/7935
+               Take dal_content into account. *)
+            let committee = tmp_to_old_committee committee in
             (consensus_content, committee));
         inj =
           (fun (consensus_content, committee) ->
+            let committee = tmp_of_old_committee committee in
             Attestations_aggregate {consensus_content; committee});
       }
 
@@ -2518,7 +2529,9 @@ let weight_of : packed_operation -> operation_weight =
       W (Consensus, Weight_attestations_aggregate aggregate_infos)
   | Single (Attestations_aggregate {consensus_content; committee}) ->
       let aggregate_infos =
-        aggregate_infos_from_content consensus_content committee
+        aggregate_infos_from_content
+          consensus_content
+          (committee_slots committee)
       in
       W (Consensus, Weight_attestations_aggregate aggregate_infos)
   | Single (Proposals {period; source; _}) ->
diff --git a/src/proto_alpha/lib_protocol/operation_repr.mli b/src/proto_alpha/lib_protocol/operation_repr.mli
index 5382636189598c55f5c83a269d6bed6a96d42c16..5dc6ccb29d1128898efb01008eb1b75474282587 100644
--- a/src/proto_alpha/lib_protocol/operation_repr.mli
+++ b/src/proto_alpha/lib_protocol/operation_repr.mli
@@ -289,10 +289,10 @@ and _ contents =
       committee : Slot_repr.t list;
     }
       -> Kind.preattestations_aggregate contents
-  (* Aggregate of attestations without dal_content. *)
+  (* Aggregate of attestations. *)
   | Attestations_aggregate : {
       consensus_content : consensus_aggregate_content;
-      committee : Slot_repr.t list;
+      committee : (Slot_repr.t * dal_content option) list;
     }
       -> Kind.attestations_aggregate contents
   (* Seed_nonce_revelation: Nonces are created by bakers and are
@@ -584,6 +584,23 @@ val pack : 'kind operation -> packed_operation
 
 val manager_kind : 'kind manager_operation -> 'kind Kind.manager
 
+(** Extracts the slots from a
+    {!constructor:contents.Attestations_aggregate} committee. *)
+val committee_slots :
+  (Slot_repr.t * dal_content option) list -> Slot_repr.t list
+
+(* TODO: https://gitlab.com/tezos/tezos/-/issues/7935
+   The following two functions are used so that despite the type
+   having been updated with DAL contents, attestations aggregate still
+   has the old logic without DAL. They should be removed once the new
+   logic has been implemented everywhere. *)
+
+val tmp_to_old_committee :
+  (Slot_repr.t * dal_content option) list -> Slot_repr.t list
+
+val tmp_of_old_committee :
+  Slot_repr.t list -> (Slot_repr.t * dal_content option) list
+
 val encoding : packed_operation Data_encoding.t
 
 val contents_encoding : packed_contents Data_encoding.t
diff --git a/src/proto_alpha/lib_protocol/test/helpers/op.ml b/src/proto_alpha/lib_protocol/test/helpers/op.ml
index ae000bf57d4855766a1cb01e7d99ce72b12c49d3..b2e6b80fa167baad06c376a32abf3fdfe171e0e8 100644
--- a/src/proto_alpha/lib_protocol/test/helpers/op.ml
+++ b/src/proto_alpha/lib_protocol/test/helpers/op.ml
@@ -165,6 +165,7 @@ let aggregate attestations =
     Bls12_381_signature.MinPk.aggregate_signature_opt signatures
   in
   let contents =
+    let committee = Operation.tmp_of_old_committee committee in
     Single (Attestations_aggregate {consensus_content; committee})
   in
   let protocol_data =
diff --git a/src/proto_alpha/lib_protocol/test/integration/consensus/test_aggregate.ml b/src/proto_alpha/lib_protocol/test/integration/consensus/test_aggregate.ml
index 5f705c710c70d55c11fcaf1fc571a07c8f1365f4..dca10743eded83929f1db7da96395bdc5ec4cf91 100644
--- a/src/proto_alpha/lib_protocol/test/integration/consensus/test_aggregate.ml
+++ b/src/proto_alpha/lib_protocol/test/integration/consensus/test_aggregate.ml
@@ -306,8 +306,12 @@ let test_aggregate_attestation_non_bls_delegate () =
       let consensus_content : Alpha_context.consensus_aggregate_content =
         {level; round; block_payload_hash}
       in
+      (* TODO: https://gitlab.com/tezos/tezos/-/issues/7935
+         Add tests with dal_content = Some _. *)
       let contents : _ Alpha_context.contents_list =
-        Single (Attestations_aggregate {consensus_content; committee = [slot]})
+        Single
+          (Attestations_aggregate
+             {consensus_content; committee = [(slot, None)]})
       in
       let aggregate : operation =
         {shell; protocol_data = Operation_data {contents; signature}}
diff --git a/src/proto_alpha/lib_protocol/validate.ml b/src/proto_alpha/lib_protocol/validate.ml
index 0c2f8be7e326d9069d90e83f064345df52a03003..5c983d4dc3d3aeea00b873ef0ab06b7f5eddee40 100644
--- a/src/proto_alpha/lib_protocol/validate.ml
+++ b/src/proto_alpha/lib_protocol/validate.ml
@@ -1061,7 +1061,7 @@ module Consensus = struct
           in
           return operation_state)
         operation_state
-        committee
+        (Operation.committee_slots committee)
     in
     return {info; operation_state; block_state}
 
@@ -1117,7 +1117,7 @@ module Consensus = struct
               | Bls pk -> return (pk :: public_keys, power + total_voting_power)
               | _ -> tzfail Validate_errors.Consensus.Non_bls_key_in_aggregate)
             ([], 0)
-            committee
+            (Operation.tmp_to_old_committee committee)
         in
         (* Fail on empty committee *)
         let*? () =