Huge fan of Legacy here. The Evolved Survivors from End Game look really neat but if you'd just want to keep it core its no problem at all-would the Stranded Starfarers be too weird to play? Fictional incongruities aside I'm also kind of wary/hesitant of playing something that has a "unique weakness of being too powerful".
Would you want to keep it Ruins, Echoes or Mirrors for the scope of Family playbooks?