Well, this film does take place before the attack on the Death Star. So there are plenty of potentially good explanations for why Mon Mothma would be on Yavin IV for a scene in RO, but not during the events of ANH.
Right. And that’s why I’m hoping that this movie will somehow logically explain her presence in this storyline when she does not appear in ANH or TESB. If it’s logical, fine. I’m all in. But if they just add her so that we have another familiar face for nostalgia reasons, well, that’s BS.