A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
You could purchase a separate ticket for the AMS-OPO segment. DL will check bags through onto KLM and protect you across the DL and KLM tickets.
However, if you're trying to get a RT award ticket, having a separate ticket for OPO-AMS might complicate the situation since you'd be checking in with KLM. Your PM status grants a free checked bag (although perhaps not on the KLM version of a BE fare), but the contract agents working for KLM at OPO might resist checking the bag through to the USA.