My daughter is only 6 months old so I haven't personally had to deal with this yet. But while on vacation I went to a large public pool with my family. My sister-in-law was at the kids pool with my nephew. She sat on the edge and played with him and his toys. Another little boy came over and wanted to play as well. The kids played and the moms sat on the edge chatting. They let the boys have their time but they were both very close by in order to keep things under control. That seems like a much better idea to me than to watch your kid from far away and do nothing when they are bothering others!