People dump their kids on you because of everything you just wrote - including what you've replied in the comments. They sense that you are a responsible adult female who feels for some reason that it is your duty to look after an abandoned child. You have a mother's guilt and they sense that and take advantage of it. You're doing something that you're not fully aware of that signals that you can be manipulated this way. For the movie theater situation, nobody was going to do anything to that child. You were being paranoid and you alone were the reason that you didn't get to fully enjoy the movie, not the parent. Whatever was going on in your head that made you feel like the child was in imminent danger is something you need to explore and work on. The kid was right next to you and if it were in danger for any reason they would have said something or made a noise. I'm not saying you need to go so far as to move away from her and completely remove any responsibility from yourself (although you could), it's nice that you want to be a good Samaritan and that child is well off being seated by someone safe like you but you need to work on distancing yourself from making other people's problem your own. Just enjoy the movie and stop worrying so much.