It seriously takes two adults to take care of one non disabled child ? Who is caring for child 2 whilst child 1 needs both of you to care for them?
How do you manage at home when one of you needs to leave the other alone with this child to go to the store (or maybe even to go to work)? What happens to child 2 at home ?

Two sets of two makes far more sense than your rather entitled attitude that it is fine to constantly disturb another passenger because you think you and your tribe are too self important to sit in pairs or further back.

I'm not a child hater - I've travelled long haul frequently with my own son (who also incidently has a disability so needs more care than the average child)both solo and with his father and I know first hand your excuses are not justified