Hi Claudia,
My heart goes out to you on this one. My little lad's going through a similar experience (but I suspect for different reasons - See All Alone posted 20Feb). Got some good advice that might be more relevent to your situation.
Some schools have an initiative to counter this using a "friends waiting area" in the playground. Older children are designated the resposibility for ensureing that their younger peers are looked after during playtimes. If a child goes and waits in this area, one of the older kids goes over and finds a play buddy for them. It might be worth suggesting a similar system to your young lady's teacher or head-teacher.
Hope this helps and good luck..
Matt

Thanks for your advice and tips..it's just great to know that this is not uncommon.
Thanks again ...REALLY APPRECIATE ALL YOUR COMMENTS