Originally Posted by
mahasamatman
And the connecting airline will generally ignore the UA-issued BPs and print their own. I don't think I've ever been able to actually use a UA-issued BP on another airline, so I don't know why they even bother.
it can be useful to show that you have inward travel, eg at security or connecting passengers lane.
OP - just to be safe bring a printout of your itinerary that you can show security in AMS in case you don’t have BPs. Also, download the Turkish app - you may be able to get eBPs on that after checking in in SFO or after landing in AMS.