Minty, could you also do some role plays with her, about what a friend does, (do friends say you cant play with us, for eg) and how to walk away?
Pretend to be a bossy girl, and get her to walk away.
Have her hold something in her hand if she's playing, but if the game turns nasty, and the others (you) are being bossy, and mean, that she's to drop what she has and to walk away. Teach her that its not ok to be mean, and it's not ok for her to stay if others are being mean. Tell her that she's not to engage, but to ask for help from the teacher.
If she has a temper, and acts out angrily, let her have a special bath mat that she has to stand on at home, to shout and stamp to download her feelings. Ask her to stamp and shout if she likes when she comes home and to learn not to act out at school. Give her a pillow to punch if she's really mad at someone- let her shout.
Make sure she's not dehydrated, and that she knows where the loos are and how to use them. A lot of reception problems can be sorted imvho by having a drink of water. Make sure she knows where her water bottle is and that she can drink from it.
Teaching her how to observe might be very useful as well, if she's eager to fix a problem which isn't in effect her business. Not everyone takes kindly to being sorted out by a third party. Ask her to identify faces and emotions. Get some magazines and cut out faces - get her to call out the emotions and write down the words for her. Put them in a scrapbook.
Caring for little ones and bunnies is all well and good, but to adopt the 'helper' role isn't useful to her in the long term. I'd discourage her helping so much- her job is to be a child, not a little helpful adult. Being teacher's little helper isn't something she should aspire to- its not helpful to her as a woman.
Ask her to draw herself in the classroom, as a blob, or circle, and the others as other distinct blobs- this might help her see herself as a distinct person who is equal (not better, not worse) than the other people in the classroom. Get the colouring pens out for a creative session. Let her draw the yard and how they play. Let her draw different scenarios- let her put smilies in the blobs to indicate who was sad, who was happy, who was angry, what she felt when X happened, etc.
Hope it works out perfectly for you.