When I should have excepted getting regected!

I have had a lot of fun with Chelsea these last couple weeks while the other kids have been in school. She is not quite old enough to start pre-school, so we are continuing with the babysitting co-op/playgroup. A few days a week she gets to play at one of her friends houses for three hours each day. One other day (Tuesdays) she gets to have her friends over for a playdate (5 of them). This has worked out great. It allows her to socialize and play with friends and it gives me the opportunity to get stuff done. Well, Friday I decided to just keep her. She was feeling a little down and under the weather. She had a fever the night before and I have been also fighting something. After playing a couple games together, she starts to cry. She says, "I want Melanie to come home and play with me." I said, "I will play with you!" She said, "No, I want to play barbies and you are a mommy. Mommies don't play barbies!" It took all of me, not to agree with her! I have never felt so torn! Hee, Hee! Some of me...ok, all of me, really didn't want to play barbies, but I am really trying to be a good mommy and spend time with my baby girl that is just growing up too fast. So, I said, "I know how to play barbies and I will play with you." AND we played and played for a good hour! So, yes mother, all those 40 barbies that were lying naked around the house, are now dressed. I can't promise they will have clothes on when you come next, however! AND I guess I was a pretty good playmate because now, every time she wants to play barbies, she asks ME to play. WHAT DID I DO! I can't just tell her mommies don't play barbies? OR can I?