Unfortunately there are "parents" who believe that the FA's are there for childcare, and said "parents" don't have the wit to think that their li'l angels could possibly upset people around them, and let them run amok because it is easier that way. In a number of ways people seem to leave their common sense at home when they travel.
But - if the seats have been paid for then, like it or lump it, they are entitled to be there. Money/miles/status shouts.....