Join Date: Aug 2006
Location: MUC (home), DUS (office), XXX (customer)
Programs: LH, AB, SPG, CC, Sixt, EC
Posts: 6,332
Why can't US check him in also for the LH flight? In that case I'd online check in with LH which is possible within 23h of flight.
At the gate for the LH flight, show them your BP and ask if they have loaded your luggage on the second flight. This information is usually connected to your BP...