Paul Johannson and Elizabeth Gracen hated each other hence killing off any chemistry between the two main characters. They have however set aside their differences and remain friends.
While Amanda has used many surname aliases or temporary married names like Darieux, Montrose, Deveraux, Dupres, Markham and LeFauve, her actual real surname is unrevealed if she even ever had one.
The character of Lucy Becker was originally written as a woman in her 20's. She was changed to a middle aged woman so that the character would not upstage Amanda.
The series is a spin-off of Highlander (1992) which is a spin-off of Highlander (1986). Elizabeth Gracen appeared as Amanda in 20 episodes of Highlander (1992) as a recurring character and made her debut in Highlander: Lady and the Tiger (1993) which she is revealed as a former lover of Duncan McLeod (Adrian Paul).
After the series, Elizabeth Gracen didn't return again as Amanda in Highlander: Endgame (2000) and Highlander: The Source (2007) and her fate remains unknown.