I may not know what I'm talking about, because I don't have kids (or just because , but aren't kids charged a % of the adult fare on Int'l tickets?

I recall an instance here where an airline wanted to charged a ton of money for a child to fly in J. Can't recall the airline, whether the parents had upgraded into J, the age of the child, etc., but it may be worth looking into before you go to the trouble of finding an upgradable itin. on the return.