I tried a similar thing and it doesn't work, despite EK trying hard - I flew EK HKG-DXB-AMS and then had BA AMS-LHR-GLA, this was also all on the one ticket booked via Qantas. But no luck.
https://www.flyertalk.com/forum/31243822-post12.html
https://www.flyertalk.com/forum/31276062-post32.html