with our playgroup, there is 2 boys who always barge in and take toys off the other kids... now, majority of the time, the mums are off chatting, whereas i stay with DD and either play with her or stand and watch her play, but i dont take my attention off her. so it makes it hard if another child comes and snatches a toy off DD.. what do i say? DD isnt the type that would scream or snatch back, she is so placid, but i dont think its fair that she just misses out on playing with what she had first... usually i just say to her 'come on, come over here and play with.......' and take her to another activity.
Hmm, I think the best thing you could do is ask the child to give the toy back and say "we don't snatch darling" etc. I don't think you should let it go, I'm not sure what that is teaching DD iykwim? Don't panic about what the parents would say, it's about teaching your child fairness, good manners and confidence.

Other parents can be a bit scary sometimes - and for that matter so can some kids