We've done several trips with up to 21 of our family members in the past, but the last trip was pre-Covid. That might impact some of the availability in the spring, but hopefully not. As a family, in the past, we managed to get a single table for all of us at 'Ohana, Boma, China (Nine Dragons in Epcot), T-Rex. We had to break down into 2 tables (which was almost the equivalent of your crew!) at Chef Mickey's, Sanaa, and Rainforest. We also had 2 tables, but in the same room, for the hibachi meal at Teppan Ido (Japan at Epcot). If your family might enjoy something like that, you might be able to get your own table to yourself.
Again, I'm not certain what these places can do now, but be open to the idea you might be ok doing it. It might not hurt to brave a long wait on the phone for WDW-DINE in advance of your 60 days to see if they might offer any suggestions. You're likely to get some here, too. I know if you look at the ADR link on the Disney site, they seem to go up to 11 and beyond for the number of people you can reserve for - but I'm not clear if that's actually doing anything at this time.
I expect you might have a reason for being cautiously pessimistic about HDDR. Seems like that's going to be one of the last places to open. But you never know, so keep your fingers crossed! Hope this all works out well for you. The memories we've had from our trips are priceless - yours will be, too.