From what I understand every sharing scene will have the MC involved too, so you don't have to worry about anyone stealing her. For Graham and Olivia I believe that there will be 2 different sharing paths, one where he is involved and one where he's just a spectator. This is just my guess, but it makes sense to me because at some point Olivia asks him if he likes D.So far i've been doing the daughter router first as my main and then the different sharing routes there are so far only a few characters i wouldn't mind sharing her with like Olivia and Graham who both only seem to want casual sex unless at some point they just want the daughter and leave you out and the other person is Georgina who could be a new Mother figure if you three lived and had fun together