Are you traveling with someone else? Why not make keep the ICAR reservation under your name and put the IFAR reservation under a fellow traveler's name? We'd also set the pickup time for the IFAR reservation to a couple of hours later than you plan to arrive so there's still time to cancel it if you get something from the UC section. Once the pickup time has passed, it's no longer possible to cancel via the app/online.

Also keep in mind that prices often change as the pickup date approaches. It's worth tracking both reservations for price drops.