There are other platforms that are ok with incest, like SubscribeStar. Sisterly Lust and Depth's Revival both did very well without being on Patreon. Tales from the Unending Void is even being sold on Steam.
And if the theme is not incest based because of the platform you chose, then you can just write the story so that the characters are described by who they are, instead of what they are to each other so that the dialogue makes sense. Give all the characters a back story that defines them individually. A good example of this is Eternum by Caribdis.
A lot of AVNs with great stories turn out bad, and I quit them early, because they let the reader define what the characters are to each other (landlady, friend, room mate,) and it never works out in the dialogue throughout the story and makes things confusing. Like I said, a bad example of this is My Best Deal. Great story, Amazing visuals, but the dialogue killed it for me. I just hope to help you avoid that happening in yours. Thanks for the reply