6yo daughter dealing with controlling 10yo girl

This is LONG, sorry. Hope it's not too confusing. I just want to handle this appropriately.My daughter is 6yo and is in 1st grade. I'll call her T.T has a friend, J, who is in 1st grade like her. Sweet girl. She has an older sister, E, who is in 4th grade. Sweet girl; helps out at Girl Scout meetings and is generally lovely. I know their mom, C, pretty well in the sense our kids are friends/in Girl Scouts together. T, J, and E play together at before-care on the school playground a lot. Never had any issues.There is another 4th grader, B (for Brat...), who is friends with E. She is very bossy and possessive of her friends, but takes it to a new level with younger girls she can "control." Last year, her target was J, who thought it was great and of course didn't see that it was an issue because she was 5. Mom C seemed to take care of it by speaking with program directors. Additionally, she's possessive/controlling of E and when E did not want to play with her, she raged out and hit her with a bike pump in the chest and left bruises. (School principal was involved, etc, and I think that's mostly resolved? Haven't followed up with Mom C on that.)ANYWAY B transferred her obsession (truly an accurate word) to T this year. Because B is now trying to control T's every move and I found out about all this stuff from last year from Mom C, I tried to talk to T about it. T said she is bossy and sometimes won't "let" her play the way she wants. I talked to her about only playing with E if she wants to play with older girls and to stick with kids her age. She started doing that because she doesn't really like B anymore.Well, now, B gives me the evil eye every time she sees me. She also will run up to T before she sees me and hovers, until I walk up then she walks away while glaring at me. No idea what's going on once I leave. Mom C says B has been nasty to her in a way that was surprising for her (and she's in education so she's dealt with bratty kids).I do not trust this girl at all. Not only has she done this to other younger girls, T is fairly trusting and doesn't think it's a huge deal (because she's 6). She knows when someone is being bossy but doesn't know what "controlling" or "obsessive" is and her trust radar is not yet calibrated lol.SO what do I do? I want to talk to the program director tomorrow just so she can look out for it, but in general, is there a way to talk to T about this? Do you have any experience with controlling kids who target younger kids? I hate seeing T unsure of what to do on the playground and like I said, I don't trust this girl (since she's already hurt one person) and I don't want T to get hurt. via /r/Parenting https://ift.tt/2xFKGQW