S.T.
while i'm a huge fan of natural consequences, i also think it's okay to discuss recurring problems with our kids too. so long as you're not interjecting yourself into the relationships, it IS our job to some degree to help our kids develop tools to work through issues, isn't it?
i really like that you take a good clear-eyed view of your girl and don't try to pass off her issues as negligible or the other kids' fault. seriously, that's a rare and wonderful trait.
what i'm not seeing in your post is how it's affecting HER. does it bother her that she can't seem to keep a posse around her where she lives? or is she sailing on oblivious to the reactions she's getting? and that's important- if she's not actually seeking solutions, that explains why you're not getting through to her.
perhaps it's a matter of presenting the same information through different channels. while i prefer a direct approach, including role-playing a little if a kid is having trouble coming up with responses, it doesn't work well at all with a kid who doesn't see a problem in the first place.
it may require a little ingenuity on your part to read with her or find a movie or discuss a situation in which the protagonist is getting plowed down by another bossy kid. keeping the touch light, you can then say 'if you were the one in this story, which character do you think is most like you?'
and resist the impulse to help her.
then if the situation arises IRL you can just remind her of the scenario, and let it go.
but you have to stay pretty subtle about it, which is a paradox when you have an unsubtle kid<G>.
might not be a bad idea to have a quiet word with the teacher and see if she has any suggestions.
i applaud you for looking for ways to help her without getting too wound up in it yourself.
khairete
S.