There aren't any!
There are rules concerning where young children cannot sit, but no regulatory stipulation that they have to be seated next to a parent.
I am not happy when young children are seated away from their parents, and I know that the cabin crew would do what they could to resolve a situation when that occurred.
However if I were you I would buy the boarding advantage or ensure you check-in early. Most airlines do have a pre-board facility for families with young children. I am not sure if that is the case here? No doubt somebody will be able to advise.