Thanks for your help, if its not her real mother then i'll skip the game
It's just for patron rules, they are intended to be real family you can feel it with some dialogue and how the story is made (at least for the sister you feel it). I honestly even forgot the mom was stated to be a stepmother at any point.
What kind of swinging this game have ?
The game is very lighhearted and perverted, so it's the "fun" kind. No drama, and avoidable.
The girls can be quite slutty and even if MC is always the favorite, he can share a number if them with some dudes if you want, mainly with his friend Kirk, occasionally with others. Kirk has an ending too. There are some possible orgies too (probably the best orgy scene I saw in a game).
Also, one of the girl used to work
as a prostitute. She stops when she becomes involved with mc, but remains quite perverted, apart from sharing her you can see some scenes of when she worked, she even fucked (bigger spoiler) her daddy)
Anyway for me it's the best game in terms of harem/swinging content.
The game is also full of netori, you sleep with taken girls (and wives) a lot. But as I said, the game is rarely serious, very laid back, lot of humor. MC is an absolute dick but not really mean, just funny.