I don't think Val is Ximena's daughter, or Santiago's. When Val and the MC talk over phone in this latest episode, MC points out that he met Ximena and not only that, but that she also portrais one of the characters in a game they both played and yet Val didn't have any reaction to it, meaning Val doesn't know Ximena, personally at least. As for Santiago, its a stretch as well. Previously it has been mentioned that Val's dad is into surfing which Santiago is not. Granted, its not much to go on but its there. Gaby and Santi are, or at least were obviously married at some point, that much is clear from the picture on the wall we see if we have sex with her if we pick her up in a bar for a one night stand after our fight with Erynn. Im sure this will bite us in the ass later if we are still on Gabi's path. MC is Santiago's son, that has been confirmed by multiple people now. Also, Gabi has a sister who is the same age as Val and has some classes with her, she was officially introduced in this latest episode, so there's no way Gabi is Val's mom.