Not sure just removing SA off patreon means that Frank will be Becca's dad. CNG hinting at it could just as easily be CNG messing with the fan theorists that push it relentlessly. Narratively, while I don't think Becca was "always" Frank's daughter (early on there was a built-in code that made Frank and Abby bio dad and daughter,) I could see CNG now making Becca Frank's bio daughter, and her using it as a proverbial sledgehammer to break the mental barrier of his refusing Abby's advances. In a "You unknowingly were banging your biological daughter and were giving her sweet, delicious creampies, what's the hangup with including your adopted daughter in the DPG now?" kind of way.
Tanya is into Ashton, as shown in the opening scene of Mythic Desires, whether they are bio siblings, step or there's an adoption we don't know yet.
I don't know how CNG has their discord laid out, but if subscribers from both crowdfunding sites go into the same channel access categories, that could cause issues as patreon will moderate off-site content, and if patrons get access to the SA channels they could act on that. This issue came up with Summertime Saga having semi-official incest patches available on its discord, though given the revenue Saga brought in every month, it was nearly the last AVN to be moderated in such fashion. Hopefully CNG doesn't allow access to the SA discord channels for patreon-only subs, as patreon could still take their crowdfunding offline.