I worry less about young children in an unfamiliar environment being stressed and crying than I do about adults that feel entitled to sit halfway into my seat because they can't fit into their own seat. I think that everyone should realize that we live in a communal world where adults and children are allowed to travel in common carriers. A grossly obese person cannot fit into a single seat. A small child cries out of distress. Not the same thing. Of course your discription of them makes your position very clear.