I have an AmEx companion voucher but I want to use it on specific dates to a specific destination.

Based on conversations I've had with BA staff on the phone previously, I've tried to do this:

1. Book the outbound flight as a single route for two people.
2. Book the return flight as a single route for two people.
3. Ask BA to book a new return flight with the companion voucher, using the seats obtained in the first two bookings.

I realise that #1 & #2 cost me more in points but my thinking was that I'd get them refunded when we got to step #3.

However, when I rang BA this morning, they basically said they couldn't do it. More precisely, they said that they couldn't guarantee that, between cancelling #1 & #2 and then booking #3, the reward seats wouldn't be taken by someone else.

I understand what they are saying to me, but is that really the case? Do they not have the ability to move those seats over to a Companion booking somehow? I don't know, which is why I'm asking people who seem to know a lot more about this than me

Unfortunately, I know that the approach my wife & I take to holidays (specific dates, specific places) doesn't fit best when it comes to reward flights. Booking single trips may get me the seats but it will burn through the points .

Thanks for any suggestions or feedback.

Regards

Philip