I have several really small credits, where even three of them wouldn't be enough to purchase even the cheapest flight. If the only way to merge them is via a $29-or-39 temporary-reservation, I'll probably have to top it off with credit card funding. Would it be better to cancel within 24 hours, or after 24 hours? It would be preferable to get that temporary credit card funding back, but if it must be turned into a voucher, that's ok.

In other words, the goal is to merge five credits under $10, all with no expiration date, some transferrable and some not (but I don't mind if they become non-transferrable).