Under age of two they can travel as a lapchild and- on domestic flights- sit in FC without additional cost. If over 2 you are probably f'd in that one of you has to be sitting with the child at all times. The best you could do- on a wide open flight- would be to use stickers to upgrade one of you, then change the child's award to the front cabin to sit with the upgraded adult, then use stickers to upgrade the second adult. More info here:

https://www.aa.com/i18n/travelInform...title=children

Or if available you could use two FC awards for one adult and the child and buy a coach ticket for the second adult and hope for the upgrade to clear.