We were at a large play group recently and my 17 month old was playing with a ball. Another little girl around the same age kept following her around and taking the ball from her. My LO is really laid back and doesn't take toys from other kids (yet) so she didn't try to take it back or anything. This happened several times- whenever my LO would find a toy, this other kid would come grab it from her! I was getting so irritated. Usually the parent will intervene and tell their kid not to take toys but this mom was either not paying attention or didn't care, so after the third or fourth time, I told the kid (very nicely), "LO was playing with that, is it ok if you play with this other toy?" At that point, the other mom finally woke up and distracted her kid away.

I usually try not to intervene when kids are playing and usually, the parents are pretty attentive so I really don't have to. In this case though, I was getting so annoyed. What do you usually do?