In February, I'll be flying to Koh Samui on two separate reservations, one booked on points (JFK-FRA-BKK) and another at cost (BKK-USM).
On the rewards itinerary ...
JFK-FRA is on LH
FRA-BKK is on TG
On the paid itinerary, I'm on Bangkok Airways.
I know that Thai Aiways and Bangkok Airways have an interline agreement at BKK, where I can check my bags all the way through to USM. However, will Lufthansa give me problems checking in my bags at JFK?