Boxed In was, once you have all the reveals out of the way, 100% incest. Here, there's some, but it's not really got too far yet as it's a much more expansive game (and of course, completely different circumstances) and also plenty of the characters are not related. So far, we have met a couple of daughters, a sister, and a niece of MC, and we have also just learned that the Boxed In family is also related, and have met the Boxed In MC's mother and her sister here.
There is no indication of netori at the moment, but I guess it might come up at some point. So far though, I don't think there are any potential LIs who are noted as already being in a relationship. In terms of adjacent content, there's potentially some form of sharing in the cards, with (amongst other possibilities) one mother talking about sharing her daughter with MC, or at least telling him she has fantasised about it and encouraging him in that direction.