Wells was Jennifer in 1 and Shue was Jennifer in 2 & 3. However, bear in mind that Shue was supposed to be Jennifer throughout the series. However, just before filming was to begin on 1, a family member had been either badly injured or killed in an accident and she was replaced by Wells. Also, IMDb says that when filming for BTTF 2 began, it was discovered that Wells had disappeared from the acting scene back in 1987 for "undisclosed reasons" whatever that means.
Wells was Jennifer in 1 and Shue was Jennifer in 2 & 3. However, bear in mind that Shue was supposed to be Jennifer throughout the series. However, just before filming was to begin on 1, a family member had been either badly injured or killed in an accident and she was replaced by Wells. Also, IMDb says that when filming for BTTF 2 began, it was discovered that Wells had disappeared from the acting scene back in 1987 for "undisclosed reasons" whatever that means.