diff --git a/src/proto_alpha/lib_delegate/baking_actions.ml b/src/proto_alpha/lib_delegate/baking_actions.ml
index 59346da12915e615d3f68fc2b648582cad4997e9..b6464b02fc13c4671ac53645c227a06f1fb29cc7 100644
--- a/src/proto_alpha/lib_delegate/baking_actions.ml
+++ b/src/proto_alpha/lib_delegate/baking_actions.ml
@@ -919,6 +919,10 @@ let prepare_waiting_for_quorum state =
       level_watched = latest_proposal.shell.level;
       round_watched = latest_proposal.round;
       payload_hash_watched = latest_proposal.payload_hash;
+      branch_watched =
+        (if state.global_state.constants.parametric.aggregate_attestation then
+           Some latest_proposal.grandparent
+         else None);
     }
   in
   (consensus_threshold, get_slot_voting_power, candidate)
diff --git a/src/proto_alpha/lib_delegate/baking_lib.ml b/src/proto_alpha/lib_delegate/baking_lib.ml
index 8c241ee2186d73e9a9d77e5431bf3ef763e28618..af3021f99cbb14a054da176568af17c22fe4e6d1 100644
--- a/src/proto_alpha/lib_delegate/baking_lib.ml
+++ b/src/proto_alpha/lib_delegate/baking_lib.ml
@@ -413,6 +413,12 @@ let propose (cctxt : Protocol_client_context.full) ?minimal_fees
                 level_watched = latest_proposal.shell.level;
                 round_watched = latest_proposal.round;
                 payload_hash_watched = latest_proposal.payload_hash;
+                branch_watched =
+                  (if
+                     state.global_state.constants.parametric
+                       .aggregate_attestation
+                   then Some latest_proposal.grandparent
+                   else None);
               }
             in
             let* state =
diff --git a/src/proto_alpha/lib_delegate/baking_state.ml b/src/proto_alpha/lib_delegate/baking_state.ml
index 20a95f3dd5d1cd8b1bcf055dad2ee8067aef2bbe..7a0228cd31a31a32724c330aab363781af3a394a 100644
--- a/src/proto_alpha/lib_delegate/baking_state.ml
+++ b/src/proto_alpha/lib_delegate/baking_state.ml
@@ -152,6 +152,7 @@ type block_info = {
   prequorum : prequorum option;
   quorum : Kind.attestation operation list;
   payload : Operation_pool.payload;
+  grandparent : Block_hash.t;
 }
 
 type cache = {
@@ -189,6 +190,7 @@ let block_info_encoding =
            prequorum;
            quorum;
            payload;
+           grandparent;
          } ->
       ( hash,
         shell,
@@ -197,7 +199,8 @@ let block_info_encoding =
         round,
         prequorum,
         List.map Operation.pack quorum,
-        payload ))
+        payload,
+        grandparent ))
     (fun ( hash,
            shell,
            payload_hash,
@@ -205,10 +208,12 @@ let block_info_encoding =
            round,
            prequorum,
            quorum,
-           payload ) ->
+           payload,
+           grandparent ) ->
       {
         hash;
         shell;
+        grandparent;
         payload_hash;
         payload_round;
         round;
@@ -216,7 +221,7 @@ let block_info_encoding =
         quorum = List.filter_map Operation_pool.unpack_attestation quorum;
         payload;
       })
-    (obj8
+    (obj9
        (req "hash" Block_hash.encoding)
        (req "shell" Block_header.shell_header_encoding)
        (req "payload_hash" Block_payload_hash.encoding)
@@ -224,7 +229,8 @@ let block_info_encoding =
        (req "round" Round.encoding)
        (req "prequorum" (option prequorum_encoding))
        (req "quorum" (list (dynamic_size Operation.encoding)))
-       (req "payload" Operation_pool.payload_encoding))
+       (req "payload" Operation_pool.payload_encoding)
+       (req "grandparent" Block_hash.encoding))
 
 module SlotMap : Map.S with type key = Slot.t = Map.Make (Slot)
 
@@ -1233,6 +1239,7 @@ let pp_block_info fmt
     {
       hash;
       shell;
+      grandparent = _;
       payload_hash;
       round;
       prequorum;
diff --git a/src/proto_alpha/lib_delegate/baking_state.mli b/src/proto_alpha/lib_delegate/baking_state.mli
index 6ce42effd2a70e481607107cf8e0aa1278e3e71e..6dd99f47911fdab84eb64c0a52e32a4cae3c67bb 100644
--- a/src/proto_alpha/lib_delegate/baking_state.mli
+++ b/src/proto_alpha/lib_delegate/baking_state.mli
@@ -275,6 +275,7 @@ type block_info = {
   prequorum : prequorum option;
   quorum : Kind.attestation operation list;
   payload : Operation_pool.payload;
+  grandparent : Block_hash.t;
 }
 
 val block_info_encoding : block_info Data_encoding.t
diff --git a/src/proto_alpha/lib_delegate/node_rpc.ml b/src/proto_alpha/lib_delegate/node_rpc.ml
index 2bd8ec0dfbf3367fff9bcda2d5c6c05ddd0e84f7..eb004bb38d5a3ee623e36f3b5e208913b4dc2991 100644
--- a/src/proto_alpha/lib_delegate/node_rpc.ml
+++ b/src/proto_alpha/lib_delegate/node_rpc.ml
@@ -86,7 +86,8 @@ let extract_prequorum preattestations =
         }
   | _ -> None
 
-let info_of_header_and_ops ~in_protocol block_hash block_header operations =
+let info_of_header_and_ops ~in_protocol ~grandparent block_hash block_header
+    operations =
   let open Result_syntax in
   let shell = block_header.Tezos_base.Block_header.shell in
   let dummy_payload_hash = Block_payload_hash.zero in
@@ -131,10 +132,11 @@ let info_of_header_and_ops ~in_protocol block_hash block_header operations =
       prequorum;
       quorum;
       payload;
+      grandparent;
     }
 
 let compute_block_info cctxt ~in_protocol ?operations ~chain block_hash
-    block_header =
+    ~grandparent block_header =
   let open Lwt_result_syntax in
   (let* operations =
      match operations with
@@ -188,7 +190,12 @@ let compute_block_info cctxt ~in_protocol ?operations ~chain block_hash
               operations)
    in
    let*? block_info =
-     info_of_header_and_ops ~in_protocol block_hash block_header operations
+     info_of_header_and_ops
+       ~in_protocol
+       ~grandparent
+       block_hash
+       block_header
+       operations
    in
    return block_info)
   [@profiler.record_s
@@ -253,10 +260,28 @@ let proposal cctxt ?(cache : block_info Block_cache.t option) ?operations ~chain
                raw_header_b
              [@profiler.record_f {verbosity = Info} "parse pred block header"])
           in
+          let* grandparent =
+            let* raw_header =
+              Shell_services.Blocks.raw_header
+                cctxt
+                ~chain
+                ~block:(`Hash (predecessor_header.shell.predecessor, 0))
+                ()
+            in
+            let header =
+              (Data_encoding.Binary.of_bytes_exn
+                 Tezos_base.Block_header.encoding
+                 raw_header
+               [@profiler.record_f
+                 {verbosity = Info} "parse grandparent block header"])
+            in
+            return header.shell.predecessor
+          in
           compute_block_info
             cctxt
             ~in_protocol
             ~chain
+            ~grandparent
             predecessor_hash
             predecessor_header
         in
@@ -295,6 +320,7 @@ let proposal cctxt ?(cache : block_info Block_cache.t option) ?operations ~chain
             ~in_protocol:is_proposal_in_protocol
             ?operations
             ~chain
+            ~grandparent:predecessor.shell.predecessor
             block_hash
             block_header
         in
diff --git a/src/proto_alpha/lib_delegate/operation_worker.ml b/src/proto_alpha/lib_delegate/operation_worker.ml
index ffb9ce8fab173ca964deb7637026f7a03b54d6ee..8222c9c9e5423517b65f99ba2851448007fe7542 100644
--- a/src/proto_alpha/lib_delegate/operation_worker.ml
+++ b/src/proto_alpha/lib_delegate/operation_worker.ml
@@ -178,20 +178,32 @@ type candidate = {
   level_watched : Int32.t;
   round_watched : Round.t;
   payload_hash_watched : Block_payload_hash.t;
+  branch_watched : Block_hash.t option;
 }
 
 let candidate_encoding =
   let open Data_encoding in
   conv
-    (fun {hash; level_watched; round_watched; payload_hash_watched} ->
-      (hash, level_watched, round_watched, payload_hash_watched))
-    (fun (hash, level_watched, round_watched, payload_hash_watched) ->
-      {hash; level_watched; round_watched; payload_hash_watched})
-    (obj4
+    (fun {
+           hash;
+           level_watched;
+           round_watched;
+           payload_hash_watched;
+           branch_watched;
+         } ->
+      (hash, level_watched, round_watched, payload_hash_watched, branch_watched))
+    (fun ( hash,
+           level_watched,
+           round_watched,
+           payload_hash_watched,
+           branch_watched ) ->
+      {hash; level_watched; round_watched; payload_hash_watched; branch_watched})
+    (obj5
        (req "hash" Block_hash.encoding)
        (req "level_watched" int32)
        (req "round_watched" Round.encoding)
-       (req "payload_hash_watched" Block_payload_hash.encoding))
+       (req "payload_hash_watched" Block_payload_hash.encoding)
+       (req "branch_watched" (option Block_hash.encoding)))
 
 type event =
   | Prequorum_reached of candidate * Kind.preattestation operation list
@@ -340,8 +352,14 @@ let make_initial_state ?(monitor_node_operations = true) ~constants () =
     committee_size;
   }
 
-let is_valid_consensus_content (candidate : candidate) consensus_content =
-  let {hash = _; level_watched; round_watched; payload_hash_watched} =
+let is_eligible (candidate : candidate) branch consensus_content =
+  let {
+    hash = _;
+    level_watched;
+    round_watched;
+    payload_hash_watched;
+    branch_watched;
+  } =
     candidate
   in
   Int32.equal (Raw_level.to_int32 consensus_content.level) level_watched
@@ -349,6 +367,10 @@ let is_valid_consensus_content (candidate : candidate) consensus_content =
   && Block_payload_hash.equal
        consensus_content.block_payload_hash
        payload_hash_watched
+  && Option.fold
+       ~none:true
+       ~some:(fun branch' -> Block_hash.(branch = branch'))
+       branch_watched
 
 let cancel_monitoring state = state.proposal_watched <- None
 
@@ -400,10 +422,10 @@ let update_pqc_monitoring ~pqc_watched ops =
       | ({
            protocol_data =
              {contents = Single (Preattestation consensus_content); _};
-           _;
+           shell = {branch};
          } as op :
           Kind.preattestation Operation.t) -> (
-          if is_valid_consensus_content candidate_watched consensus_content then
+          if is_eligible candidate_watched branch consensus_content then
             match get_slot_voting_power ~slot:consensus_content.slot with
             | Some op_power ->
                 pqc_watched.preattestations_received <-
@@ -454,10 +476,10 @@ let update_qc_monitoring ~qc_watched ops =
       | ({
            protocol_data =
              {contents = Single (Attestation {consensus_content; _}); _};
-           _;
+           shell = {branch};
          } as op :
           Kind.attestation Operation.t) -> (
-          if is_valid_consensus_content candidate_watched consensus_content then
+          if is_eligible candidate_watched branch consensus_content then
             match get_slot_voting_power ~slot:consensus_content.slot with
             | Some op_power ->
                 qc_watched.attestations_received <-
diff --git a/src/proto_alpha/lib_delegate/operation_worker.mli b/src/proto_alpha/lib_delegate/operation_worker.mli
index 295eafeddc6c6760e5309e3351d318b0da090228..944bfbd54fb98cba72f247e0cc8f089603c6fb23 100644
--- a/src/proto_alpha/lib_delegate/operation_worker.mli
+++ b/src/proto_alpha/lib_delegate/operation_worker.mli
@@ -44,6 +44,7 @@ type candidate = {
   level_watched : Int32.t;
   round_watched : Round.t;
   payload_hash_watched : Block_payload_hash.t;
+  branch_watched : Block_hash.t option;
 }
 
 val candidate_encoding : candidate Data_encoding.t
diff --git a/src/proto_alpha/lib_delegate/state_transitions.ml b/src/proto_alpha/lib_delegate/state_transitions.ml
index ae70c3298bbd863b963d4123b92b533740c02d70..7c99ec4c643123e6bc1e4b09e4f90d2991b56f42 100644
--- a/src/proto_alpha/lib_delegate/state_transitions.ml
+++ b/src/proto_alpha/lib_delegate/state_transitions.ml
@@ -554,7 +554,7 @@ let prepare_block_to_bake ~attestations ?last_proposal
           Operation_pool.level = predecessor.shell.level;
           round = predecessor.round;
           payload_hash = predecessor.payload_hash;
-          branch = get_branch_from_proposal state.level_state.latest_proposal;
+          branch = predecessor.grandparent;
         }
       in
       let aggregate_attestation_feature_flag =
@@ -660,7 +660,7 @@ let propose_block_action state delegate round ~last_proposal =
             Operation_pool.level = proposal.predecessor.shell.level;
             round = proposal.predecessor.round;
             payload_hash = proposal.predecessor.payload_hash;
-            branch = get_branch_from_proposal state.level_state.latest_proposal;
+            branch = proposal.predecessor.grandparent;
           }
         in
         let preattestation_filter =
@@ -669,8 +669,7 @@ let propose_block_action state delegate round ~last_proposal =
               Operation_pool.level = prequorum.level;
               round = prequorum.round;
               payload_hash = prequorum.block_payload_hash;
-              branch =
-                get_branch_from_proposal state.level_state.latest_proposal;
+              branch = proposal.predecessor.shell.predecessor;
             }
         in
         let aggregate_attestation_feature_flag =