Join Date: May 2012
Location: Munich, Algarve, Sussex or S.F Bay Area
Programs: Mucci, BA Gold, A3*Gold, LH SEN, HH Gold, Marriott Plat, IHG Plat Amb
Posts: 5,663
Check in online for the 2nd leg so you have a BP. This will also assist if BA make a fuss through-checking your baggage. Normally it's no problem but sometimes you can get questioned.
You'll need to claim your baggage in JFK anyway to pass customs but simply redeposit immediately after customs at the American transfer desk. Don't forget AA depart from terminal 7.