Probably. Even though it's a dream sequence and not actually happening, it's still a MC fantasising about a family member in a sexually graphic way and could fall foul of the Patreon Purity Police.
Allowing players to input the relations at the start of the game does seem to work as there are other games that do it. The trick is to ensure that both the story and dialogue can work for the Patreon-safe version and the "true" version.
I would make a separat patch that people can download here.
That should be pretty straight forward (famous last words!). If I use a variable to define incest or no incest route I can then use an If / Else statement to have 2 different lines of dialog for times I cannot cleverly write ambiguously and have to use Mother or Other.
Do you see more risk in having it built in from the start or is it just easier to have a patch that changes the defined names.?
Probably. If the patch is hosted elsewhere you could even claim it to be "fan made". Should appease Patreon even more.
I'd be wary of doing that because I believe the game A Family Venture did something just like that by including a hidden button on the opening splash screen that activated a secondary script file to restore the incest to the game and the dev got in trouble for it and now it has a separate "fan-made" patch. So I think that even having something in your game's code to activate incest dialogue is against Patreon rules, but if someone mod's your game to put it in or you include the option to define the relationships at the start, then Patreon will overlook that.
With all due respect for that dev, that was the most stupid incest safety measure I ever saw in these games. The guy wrote "if you want to play as incest, click here" everywhere and even the warning in the splashscreen changed saying that it had incest now after clicking the button. That was really poorly applied.
