Originally Posted by A351

You may be able to get QR to check your luggage onto EK384 to save the hassle of getting out at BKK to collect luggage, check-in & come back in.

Even if your reservations are made on two separate bookings, some airlines will tag your luggage onto the other carrier's flight. CX have done this for me twice in the last few months on my SIN-BKK (CX) connecting onto BKK-AUD (EY) and also SIN-BKK (CX) onto BKK-DXB(EK). You will have to get your boarding pass for EK384 at the transfer desk at BKK so have a copy of your EK reservation handy to get through the transit point.

Of course, some airlines will say they cannot even though they can.... and BA is one of them!

PS:
If QR check your luggage on to connecting EK384, you must give the BKK EK transit check-in staff your (QR issued) luggage tag so that they can enter the tag no into EK's system.