How and how much do you go about correcting this behavior? We had friends over last night and obviously the toddlers kept taking toys from one another. DS is going through a bit of a "mine" phase and when he would yell "mine" and steal the toy, I would correct him, talk about sharing, and make him give it back to the kid. But, I felt like I was constantly on top of him the whole night and the parents kept insisting it wasn't a big deal. I just don't want DS to become a bully. The other kid is several months younger and much smaller than DS.
What do you all do?