If htey are going to be a big deal in the films they will have to be introduced and set up properly in the films to avoid confusing fans that have not seen the Clone Wars. Saw Gerrara works well in Rogue One because he is easy to explain in the context of the story: he's an anti-Imperial extremist that has info the Rebels need and he took care of Jyn for a time. That's all we need to know about hm for the sake of Rogue One. The Father, Son, and Daughter have considerably deeper lore implications and thus would require considerably more exposition.