I was working on a response to this at work and got interrupted. I thought I hit submit, but guess I didn't get that far.
Changing the name of the group or organization wouldn't necessarily creating something new. If the group is expected to handle adding a kid of the opposite sex and not miss a beat I think they could handle a name change (although it would be expensive to change flyers, websites, signs, etc. so maybe it wouldn't be the best idea).
Regardless, I fail to see a valid reason to even consider encouraging a boy to join the girl scouts or a girl to join the boy scouts. Heck, we can't even use the term congressman any more without some feminist or PC group pitching a fit. Groups have got to make up their mind. Do you want to be included or do you want some great form of separate recognition.
I may not have all of the answers, but the reasons I'm using are valid to me and many others.