One of the most irritating things about this game, is the Dev continuing to refer to Susan and Phil as step-parents when it's very clear that they aren't. Adam and Libby are adopted children, which means Susan and Phil are legally their Mother and Father. This has been pointed out many times, yet the Dev continues to falsely call them stepmother and stepfather, presumedly because of some baseless fear that Patreon will object if he calls them Mom and Dad. I don't know why, because as long as it's been clarified in the dialogue, that they are both adopted (which it has) then their shouldn't be a problem? Jo is Mike and Sally's stepmother, because she's married to their real father, and he's currently in prison. A step parent doesn't have any legal authority over children in their care, beyond being designated a proxy by/for the real parents or legal guardians. And this is very obviously not the position that Susan and Phil are in. Legally, they would be referred to as Adam and Libby's mother and father, and it beggars belief that Adam and Libby would not refer to them that way themselves.
The game is set in California, where having sex with adoptive children, is not regarded as incest. In some US states it is, but in most it isn't. If the Dev was really concerned about this, why would he insist they were adopted children? He literally could have changed the backstory, with minimal effort, to make Adam and Libby, the children of a former spouse of either Susan or Phil who subsequently died, and then only later on they both got together and married. Then both of them could have been actual step-parents. All he would need to do, was omit the part about Susan and Phil becoming an item at college. They could still have met up there initially, but only become actual partners at a later stage. Then it would all make sense. But currently it definitely doesn't.
Why, the Dev insists in referring to them in that way all the time , I just don't know. Because regardless of what the actual legal definition of their relationship with Susan and Phil was, Adam and Libby would still refer to them as Mother and Father. And as long as it states clearly in the dialogue, what the real relationship is, it's not necessary to keep reminding us, over and over again. Particularly, when it makes absolutely no sense anyway.