Upgrade voucher – add return leg when released, like you can with a 2-4-1?

[DJP31]

I’ve searched and couldn’t find anything conclusive enough to avoid the need to post. As per the topic title, if I book the outbound using an upgrade voucher, can I phone BA to add the return leg once it’s released, as you can when using the Amex 2-4-1?

I’d like to be sure of my ground before commiting myself.

TIA

[NorthernLass]

There are posts in the dedicated thread which indicate it can be done, but depends on how knowledgeable/helpful the agent is.

[RTS]

Agent specific.