Yes they do interline with LH. Done it both ways from AA to LH and the reverse many times. Bags made it every time. Will need a copy of both itineraries at check-in. They can't check you in for the other flight segment.
No need to collect bags at FRA; they're checked through
Last edited by SFOJFK; Aug 6, 2008 at 12:25 am
Reason: Forgot to add that bags are checked through.