S.D.
This is kind of a tough one. My suggestion is to talk to your friend. Explain to her just what you have explained here, that your daughter is a little sensitive and the grabbing, etc is starting to get affect her in "not such a good way." Try to work together to help the children get along. Remember, most children's actions and behaviors are learned either by other children or adults. If the children see you working together to come to a solution, it may show them how to work things out.
Another suggestion is if you're new to the area, look for a local MOMS Club. It's a support group for mothers and they have play groups and other activities. You will meet other mothers sharing similar experiences. Go to International MOMS Club and you will be able to find a club near you!