Keeping Bags on DUS

Thinking about skipping the 2nd and 3rd leg of an outbound trip. I think I should be able to keep my bags in DUS and just leave since it is my first Euro stop. I have separate itineraries for both going and returning so that shouldn't be a problem. My only concern is the bags and/or if any immigration issues, I have to check bags for this trip.

First itinerary:
SFO -> DUS -> LHR -> AMS
Air Berlin, British Airways, British Airways
(I really wanted to go to AMS but it was the only way to book the award ticket)

Cruise AMS -> BCN

Second itinerary:
BCN -> PHL -> SFO
(separate reservation)

So I'm thinking I could hop on a cheap train from DUS to AMS and save many hours of flying via LHR. The train is 2.5-3 hours vs landing in DUS at 1:40pm and not getting to AMS till 10:00pm. The first segment is Air Berlin where I'd keep the bags and miss the 2nd to legs on British Airways. Should I be able to keep my bags and not recheck them?

I don't really undertand your question.
- If you short-check your bags to DUS then of course you can keep them.
- If they are through-checked to AMS then of course you won't have access to them.

I think the OP does not realize that in Europe customs (and luggage) is not handled on your point of entry to EU (like in US), but at the final destination. Norway being the notable exception.

Maybe he thinks that it is in Europe like in the US where you automatically get your bags and you have to carry them through customs.

As others have said, unless you convince agent at SFO to short check bags as SFO -> DUS, your bag will end up in AMS.

If you proceed to baggage claim at DUS after the AB flight, you will not see your bag.

The only question is, does Europe does positive passenger/bag match on DUS->LHR, LHR->AMS? If they do, maybe they will offload bag at DUS when they see passenger is not on flight. But you are still running the risk, they miss the fact you were not on the flight, and the bag proceeds to LHR and AMS anyway.

Thanks that answered it. I'm more so used to the US where you walk your bags through customs at your first stop. Who knows, maybe I'll get a nice agent that will only check to DUS.

Unlikely but possible. Also, you've said it's a separate reservation, but understand that the moment you skip a segment the entire rest of the ticket is cancelled.