I did include "and a few threesomes you can have with him" in my post. That's one of them. Another is Edwin and Ian having threesome with Felicia early in the game. And yet another is Edwin's threesome with Mina and Felicia, where you can opt to sit in the cuck chair for a bit. I guess if you really stretch it, then Edwin can also influence Mina to get involved with Veronica, which you could also consider some sort of sharing (depending on whether you subscribe to "if it's with another girl then it doesn't count" or not)
However, those are in circumstances where Edwin's relationship with the involved girl(s) is at best casual. I dunno, this game just doesn't strike me as one where this would be any sort of in-depth interest in exploring this area in combination with dedicated relationships.
