Okay. You've won him/her over. Now it's time to meet his/her friends and family. Which is more important? Winning over his/her mother or the best friend(s)?
Obviously, best case senario is to be so damn charming you hit a home run with both. But in an either/or situation I'd have to go with the best friend. The child is somewhat used to going against mom. However the friend can take a bat to the kneecaps of a good relationship and bring the whole thing crumbling down.