Your only responsibility is to your daughter and future grandchild. You owe nothing to the 'BOY'. Send him home to his own family and then take him to court for child support. Don't fool yourself into thinking he's going to grow up over night just because he got your daughter knocked up. Think back a few years. Were you mature enough at 17 to financially support a family of three? Most of us guys aren't mature enough for that until we're in our mid 20's. Your daughter and grandchild are going to take a backseat to his friends and partying. Get a court order and let that 'boy' answer to a judge.
This is CABL.com posting #211623. Tiny Link: cabl.co/m3dr