Is this YOUR 17 year old? (I hope not...) Though I'm lucky enough not to have your problem and I guess I'd want to say "there by the grace of God go I", I would also want to ask you where you've been while your daughter was out doing this stuff. It's hard to control your child AFTER you've allowed her too much freedom and not supervised her enough so that she had the time and ability to be out catting around.
I DO think that I'd be talking to this 22 year old about his intentions toward her if I were the mother. Sometimes just coming face-to-face with this might make someone that age stop and think and realize that there is a reckoning. Is the 22 year old in college? Is he out working? Is there a reason why he can't connect with women instead of doing this with a girl? Those kinds of pointed questions might make a difference.
Perhaps counseling might help the girl come to an understanding of why she doesn't respect herself enough to stop sleeping around.
At the very least, I'd be getting her depo provera shots because I would NOT want to be a grandmother. She should be using condoms to hopefully prevent STD's. A crash course on nasty STD's would be top on the list, that's for sure.
I haven't looked at the website someone provided for the state of Wisconsin, but I have to say that if this girl has been 17 for a while, that she is probably is old enough to know what she is doing and I don't think I'd be reporting on a 22 year old (30 or 40, yes) and trying to get him registered as a sex offender. Ascertaining his intentions by talking directly to him about his responsibility should he become a father would be more appropriate.
Dawn