I have to visit sons in YYZ and YVR. It is much less expensive to book a RT LHR-YYZ than any other possibility. Travel between YYZ and YVR will be by land (or by cheap low-cost air) as I also need to visit friends and cousins meaning many stops, so that expense does not count in my BA calculations. To get double TPs I need to book on BAH both the flights (in Business class) and a car rental (5 nights).

If I book the car in YVR on BAH will that count to get the double TPs, even though I am not flying there on BA?

I just did a trial booking and it shows that BAH will allow me to make that car rental at YVR For dates selected total price is just over 2500 GBP with the car which is much better than open jaw (LHR-YYZ then YVR-LHR).

Thanks for advice.