stifiling e's creativity

My girls can spend hours playing together. A big portion of this is role-playing, where E is the mommy and A is the daughter. Or E is the teacher and A is the student. Never vice versa.

Often, I'm drawn into their games...not as the mommy, mind you, but as the grandma or the teacher or dance teacher. And, most times, I'll play along without a problem.

But, yesterday was not one of those days. We were playing on the swingset, and E was handing out the roles.

E: Okay, Mommy, you be A's mommy. And, I'll be the girl who is too old to have a mommy....
Me: What do you mean "too old to have a mommy?" I'm old, and I have a mommy! Daddy has a mommy, too! Besides, you'll always be my baby. So you'll always have a mommy!
E: Okay...how about you be A's mommy. And, I'll be the girl who lives far away from her mommy so that's why she's not here.
Me: I. Beg. Your. Pardon. You will never, EVER live far away from your mommy, do you hear? You will live close to your mommy forever, so I can come and visit you!
E: Okay. How about you be A's mommy? And, I'll be the teacher.
Me: Sounds good to me.