Currently this is correct and the only way to do this.
I have a Quest and a Quest 2. I have the multiuser and app sharing on my Quest 2. I have my main account, lets call it account A as the main account on both headsets.
On my Quest 2, I have a secondary account (account B) signed on as well. To play with my son, I have to sign into the secondary account on my Quest 2 and I have to play on my Quest.
It is a strange setup and I'm sure it will change, but as far as I know, this is the only way to play multiplayer if you own 2 headsets and only want to purchase the game once.
i7 8700, 16GB, RTX 2080 TI, Rift CV1 | i5 4690K, 16GB, GTX 1660 TI, Rift CV1 | Quest | Quest 2
We bought a second headset and I thought I had to login in with my facebook where the other one is under my husband's. We've both added each other as 2nd accounts and enabled the app sharing. We haven't tried playing against each other in any games other than Dead and Buried II and I could only play it on my headset while signed-in under his name. And then there were 2 of us in the game...confused alot of people in there. Only one of us could chat though. I hope the next rollout allows for app sharing across family accounts.