Hi all -- my first time back on these boards in quite awhile!

I'm in the process of planning my honeymoon from Washington DC to Bali in Feb/Mar 2022, and in reviewing flight options that are available to book with AA or UA miles, it seems like (at least on the outbound) Cathay Pacific is my best bet, doing DCA-BOS-HKG-DPS.

It's still too early to book my exact flight date, but looking at other dates in Feb 2022, it seems like only 1 first class seat on the BOS-HKG is available to book with AA miles; if I search for 2 pax, the first class option doesn't even show up. From some searching on the boards, it seems like this is standard for only 1 first seat to be available with miles on this route, but what I'm not clear about is whether more seats ever get opened up later on down the line to book with miles, if the seats are not otherwise bought. Does anyone have experience with this scenario?

I'm also considering booking 2 separate itineraries, one in first and one in business, in case another first seat does open up for a miles booking, with the idea of then changing the business seat changed to first (not sure if they could just do that for the miles difference, or if I'd need to cancel the original business itinerary (assuming with some penalty/cost?) and do a new booking to grab the first class seat). Or there's always the option of hoping for a miracle upgrade at the airport by playing the honeymoon card. Welcome any thoughts on that idea of having us be on two separate itineraries. It would stink if we ended up being split between first and business, but since it seems like the Cathay business class seats/arrangement doesn't lend itself well to people interacting anyways, maybe it's not such a big deal?

All views welcome. Thanks in advance for the help!