hihi, sorry for late response :) i'll check it out again whenever i can (unfortunately cant right now due to dealing with multiple projects and personal things)
to get Oliver, Edward's and Zip's ending - you have to pick to be the mean personality and bully claire, then afterwards if you see Oliver anywhere you have to help him out in some way so that he can let you into his gang (IIRC. I don't know if this is the exact way since it's been so long since I checked in on FPN, but it's still worth a try!). Hope this helps and thank you for your comment!