You should do a search for cub scouts and/or boy scouts on these boards (search box on left). There has been a good amount of discussion on your question.
I personally don't understand why these groups need sponsorship. Has never made sense to me. A cub scout troop and a PTO are completely different.
I'm looking for advice on the PTO officially sponsoring outside clubs and organizations. We've been approached by a few organizations (Boy Scouts, civic clubs, etc), asking us to sponsor them so they can use the facilities for free and to say they have an "official" sponsor.
We're concerned that if we say yes to one, we'll have to say yes to everyone to avoid the appearance of discrimination.
The second concern is that they want to use our 501(c)3 documentation to set up their bank account. They said it's just to prove the "sponsorship," but we are uneasy about it.