Running Away-cross post

Our 4.5yr old runs away from me in public every time we are out (adopted 9/07). To help with this, her counselor said she has to be in a stroller, cart, or on a least in public, until this behavior is stopped. So, I've used a cart and stroller for the last two weeks. We have of course ran out of breath explaining safety to her, and how much we love her, don't want to lose her, etc., here. She doesn't care or doesn't get it. We have no idea what is behind this behavior. A developmental delay, A RAD behavior, processing issue, emotional issue? We have no clue, but we are keeping her safe thru this. Today we all went to ToysRUs to look for Christmas presents, all seven of us. I asked my husband if he wanted her in her own cart, or the cart with her 2yr old sister. He wanted to try something new, and see if she would run away from him. Surprisingly, she stayed with us the whole time. Fancy that! I thought maybe something has helped, maybe she's figuring things out, etc. Good times. As we were leaving the store, I took her to the bathroom. We were in the same stall so I could watch her as we took turns using the facilities. She went first. When I went to the bathroom, I caught her from making a break when she opened the stall. This is of course as my pants are down. We then left the bathroom (next to the entrance/exit), where she immediately ran away from me. It took less than one second. Fortunately, she tried to run out the "entrance", so the doors wouldn't open for her. Thank God no one walked "in" the entrance at that time, so she was just standing at a shut door. I yelled her name as she ran away from me, and yelled her name as she stood at the entrance. She just scares me to death. There is a very busy parking lot right in front of the store. She could have been killed running out there if the door was open. So I politely took her hand saying nothing, left the entrance, and went for the exit. Back in the car we had a chat with my husband. I asked her why she runs away from me. She said "I don't know". I asked her why she stays with my husband. She said "because I want to". I thought I need to come here and ask for advice on this. I just took a much needed nap, since my husband is off work today. While I was sleeping, my husband went over the same information with her that I have conveyed. This time he told her that she will have to wear a leash if she runs away again. She wasn't too happy about that prospect. Any thoughts on the "why" behind this behavior, and any suggestions would be much appreciated. Another tidbit: she has told us she doesn't want to live with us because she wants to live with a bio relative (extended family member). That person, plus bio parents have lost custody of her (for countless reasons of horror), and there are restraining orders against these individuals. Not to mention, the whole entire set of extended family members each and all applied to adopt the girls. They were all denied.