I NEVER played a along with the imagniary friend! I am the mommy, the boss and I believe that my children need me to be "sane" and it actually allowed them to explore their imaginary friends without worrying that they were altering the world. Too much control for my kids is and was too much for them. When I did play along, my little one would ALWAYS make sure that I knew it was just a game. So, I knew it bothered her if I played too. When I played along with my older daughter when she was little...she took it way too far...never coming back. She told people her name was Gloria...for a very long time. 6 months? After about 3, I just let them believe that her name was Gloria, but I think if I kept correcting her, she would have changed her name on her Birth Certificate. I try to stay far away from those imaginary friends. Moms have no business in that world...we mess things up! I just say, roll with it....but don't play along. If the "friend" needs a chair, let your child get the chair...chances are that the work will become too much and she will just let the "friend" share a chair with her. In public....say.."FRIEND is your friend and you need to make sure she doesn't distrupt things." When the resposibility is theirs only, it can become overwhelming and the FRIEND will become less important!