I was on a *A award UA ticket from FRA-IST-AYT on LH and TK metal. The LH counter was able to check bags and give BP for both flights. When boarding the TK flight from IST to AYT the agent looked at the LH pass, looked a bit confused.. ripped the pass in half (not on the spot made to tare) and give me 1/2 of it back.. I boarded with no problems and my bags made it..

I have had problems with boarding passes in the past, I have always been able to check bags to final destination.

UA Ticket (A* Award) FRA-LIS (LH) LIS-TER (TP) LH was only able to get me BP to LIS and used the TAP transfer desk to get my 2nd BP. On the way back TAP from TER-LIS was given BP from the (S4) SATA agent (TAP partner handling agent) but they could not give me the LIS-FRA pass for a LH flight. When I got to LIS when to TAP transfer desk, they could not help. I had to go out to main check in area to get LH BP, and only middle seats were left..