JAL Mileage Bank - Infant tickets

I am looking at buying AA tickets composed of solely JAL flights, for example pus-nrt-bos and return. The AA tickets are chepaer than JAL. JAL also offers an infant rate as long as travel begins before age 2. Daugher would turn 2 during the trip. Thus, would I have any trouble buying the adults tickets on AA
and then dealing with JAL to add the infant ticket. I assume that AA would give a confirmation nuamber that would work on JAL.

PusanFlyer, if you're still around, I'd be curious to hear how your scenario turned out. Was the infant allowed to book a ticket on JAL without an adult fare tagging along with his itinerary?