One converted to return?

[Indy500]

I have 2 one way CW Vancouver flights booked for ‘26. Dep from LGW and returning to LHR. These were date critical flights so booked them as 2 one-ways to get the correct flights. Is there any mileage or need to ask BA to convert this into a return booking and is that even possible as we are using LGW and LHR. TIA.

[BA Flyer IHG Stayer]

Separate bookings can’t be merged or combined to form a single one.

This isn’t an issue if it being ex LGW returning to LHR. It’s a ticketing issue.