Amex voucher - changing route (and possibly cabin)?
 

Looking to travel to WAS early next year using an Amex voucher. Ideally, we would going outbound to BWI in WT+ and return from IAD in CW.

On the dates we need, outbound to BWI is currently not available for redemptions in WT+ (nor in CW), so I'm about to book my 'next best' option, which is outbound to IAD in WT+ (and still return from IAD in CW).

If redemption seats to BWI open up later (as I suspect might well happen), will I be able to:
a. switch the outbound from IAD to BWI (still in WT+, if available)?
b. switch the outbound from IAD to BWI, AND pay an extra 24,000 Avios to upgrade to CW, if WT+ is still not available?

In the past, I've managed to switch airports (between BWI and IAD) and cabin (between WT+, CW and F) successfully several times, close to the date of travel. But those were always one-way redemptions, one person (no voucher) so it was easy to book the new flight and just cancel the old one (just paying the £35 fee).

This time, using the Amex voucher, I'm anticipating I'll need to keep my original booking (to avoid losing the return flight), and ask BA to process it as a change of route (creating an open-jaw) and possibly change of cabin also.

Can anyone see anything in the voucher rules (or precedent) that would stop me doing this?

Yes no problem, although worth looking for CW or F rather than WT+.

No possibility of F to BWI (it's a 3-class 788).

I think it's more likely that availability will open up in CW rather than WT+. But in the unlikely event WT+ becomes available, then (for various complicated reasons) I will probably need to go with the cheaper option (saving 24,000 Avios total plus £43 per person).