OP is traveling nonrev standby on the domestic UA segment.

I would by no means plan on having the bags checked through by LH and if OP "misconnects" (to the extent that this is all on one ticket), there won't be any rebooking beyond rolling over to the next flight, presumably still nonrev standby.

OP is simply going to have to leave this to check-in and either go to midfield or international arrivals depending on whether his bag is checked to IAD or to his standby destination.