I’m far from an expert (and I didn’t even stay at a Holiday Inn Express last night) and my comments do not address the possibilities of flight cancellations (for which an award ticket and paid ticket would be handled differently) and the issue of seat selection and changes, but FWIW …

For Plat and 1K and GS on United, there are no fees to cancel an award ticket and redeposit the miles. (Gold and Silver pay reduced fees.) If you are Plat or above, you could book the award seat and then try to purchase the 3 tickets and if unsuccessful, cancel the award ticket.

United allows full refund for paid ticket cancellations if the cancellation is within 24 hours of purchase (might even be midnight of the next day but probably not worth pushing the limit). So you could purchase the 3 tickets and then, within 24 hours, try to book the award ticket and if unavailable, cancel the paid tickets.

Either way, as I suspect you have already considered, it would be prudent to know award availability and prices for the flights you are considering prior to commencing any process.