Yes, of course, there are missions in vanilla GTA SA where families or sets are mentioned, but if we are talking about the mission “Family Reunion” from vanilla GTA SA, then my duo project is a little about something else, namely about disintegration and not unification.
Here is the site from which I took information about those events
https://gta.fandom.com/ru/wiki/%D0%A1%D0%B5%D1%82