If you show your AY ticket to QR at EBB, they should be able to check your bag through to HEL - they have the published policy of checking through bags on separate tickets if your onward flight is operated by a oneworld partner. I did it most recently on a totally different routing (SEA-QR-DOH-QR-KTM-MH-KUL), and it worked beautifully - QR was even able to issue my MH boarding pass for KTM-KUL.
I definitely would not change from QR to BA for DOH-LHR - T4 has been doing a lot better than T2/T3/T5, so QR is a great carrier to be flying rn.
Last edited by PVDtoDEL; Jul 17, 2022 at 6:46 am