Originally Posted by jerry a. laska

Actually, I'm not sure you are entitled to ORC with BAEC unless BA sends a request off to AY and AY chooses to provide you with the ORC. Normally, when BAEC receives an ORC request due to a rerouting by another airline (most commonly we see this with AA), BAEC will send an ORC request off to the other airline.

ORC is something that the airline causing the rerouting will provide, it doesn't necessarily mean that another airline that you choose to credit to (in this case BAEC) must provide ORC if they weren't responsible for the rerouting.

For example, BAEC provides in the t and c's that they will provide original routing credit when BA involuntarily reroutes a passenger:

https://www.britishairways.com/en-gb...and-conditions

If I understand correctly you were booked with AY LIS-HEL (-DEL) and you were rerouted by AY onto BA for LIS-LHR-HEL (-DEL) or maybe LIS-LHR-DEL. BA wasn't responsible for the rerouting, AY was; AY could choose to provide you with ORC and even provide that credit to BAEC but I don't think that BAEC will provide the ORC on their own initiative unless they choose to do so ex gratia as noted by c-w-s.

This has come up before with AA flights and requires BAEC to send off the ORC request to AA and then await AA's decision to grant or refuse those requests. I think you need to ask BAEC to request ORC from AY.