I've looked around on FT and united.com and could not find a clear answer to this question. If I missed it, feel free to point me to that answer.

I have an international ticket that I'd like to use miles+copay to try to upgrade. My concern is that my boss may join me on the flight last minute and, if he does, I'll want to get back to Y+ to sit with him (he's not an upgrade type ...).

Is it possible to cancel a miles+copay upgrade AFTER it has cleared? Will my original fare class need to be available in order for me to get back into Y?

The United website (here) states: "If you cancel your MileagePlus Upgrade Award miles and co-pay may be refunded for the applicable redeposit fee."

But has anyone had experience canceling an upgrade award AFTER it has cleared?

As a MP Gold, is the fee to redeposit $100/person (see here) to make this cancellation?

Thanks.