Well I think the main thrusts of the advice above applies to you. Theoretical Seating should work out what to do, but given the age of your children in particular, then you will have certainly end up as a 1 plus 1 seating arrangement as a minimum. If you are more fussy than that then you pay. You are right that you may not be the only parent on board, but Orlando isn't too populated by status holders on the whole. And by all means ring up between 3 and 2 days to travel to make sure all is well.