Gosh I'm so so sorry this happened to you and your daughter, it's just awful!
Have you spoken to your daughter about her thoughts on the baby? Yes she is still young but she obviously knows the baby is a result of what happened? I really don't mean to sound rude or anything but she probably has her own feelings about the baby, she might resent it, be scared etc, I would be talking to her about how she really feels.
I so hope they catch these evil evil men, what a truly horrific thing to have happen to you, I'm so sorry!
You sound so incredibly strong!