Congrats Vessence on making a decision that was best for you and your family & after careful consideration. Male participation in a child's life is very important. But just because you intend for the birth father to participate doesn't ensure that participation. Women can not hinge family planning on the presence or absence of the man in the child's life... 

I hate to say this, but there is a very high chance that when she remembers these men entering the room and left without penetration that what really occurred is that she was going in & out of consciousness. There is a possibility that she was going out of consciousness during the assaults and coming back into consciousness afterward as they were leaving or during physically jarring moments like falling to the floor or doors slamming, etc. Also depending on if she attempted to wash herself afterward or if she waited too long to do a rape kit - they would not be able to detect DNA.