We had kids meals in c and f on cx and sq.
I am sure you can find smth to share on ua even if they dont have dedicated meal but i would bring a few packs of kids food and milk anyways - in case they dont like airline stuff.

i doubt kids <2 eat turkey sandwiches btw and your attitude seems rather confrontational even before the flight. Airline business is not really designed to take care of infants so its your responsibility. .