Thanks for the detailed responses. I understand that the XPUBS can be created from the seeds. I shot off that reply a little too quickly while I was heading out the door to teach a class. I see the pattern now and appreciate that the XPUBS would help to prevent any privacy leak. That leaves me questioning how would the wallet be recreated with just the XPUBs. This is where my knowledge starts to get thin. But as I understand it, seed order, derivation paths, wallet idiosyncrasies, xpubs vs zpubs, etc. impact the structure of the wallet and, in turn, the addresses. 

I pondered about using passphrases (mnemonic-I am assuming you mean from the seed wordlist--and otherwise). I read about some suggesting to use child seeds for that purpose. I think that will complicate things, more copies to back up and remember their purpose; I need to consider others that should be able to pick up where I leave off. As for the child seeds, I see a a security risk. I plan on using tamper-evident bags/family/bank deposit box.

I heard of someone using an air-gapped computer to make an encrypted file of one of his multi-sig seeds. Thereafter he uploaded it to Bitwarden or Proton. His thinking was it was as good as Casa or Unchained. Makes me wonder if even those companies are safe.

This is interesting.  The consensus I have come across seems to be to keep each seed phrase with a copy of the descriptor. I am aware that would be a compromise in privacy, but it would also ensure that none of the XPUBs are not lost. I was also under the impression that the XPUBS alone are not enough to restructure the multi-sig wallet (at least not easily), another reason for the descriptor redundancy. That leads me to my first issue. One that I am still wondering about: would a change in hardware brand conflict with the saved descriptor? Would changing one of the saved keystores (registering via a different HWW, but using the same seed) cause any issues? I plan to test this myself. It will be a while before I can get my hands on an additional HWW, just being impatient.

Greetings. New member here, but not new to BTC. It's been a few years and now that feel that I have gone down the rabbit hole deep enough, I am exploring multisig setups. I have a couple of questions. The first: say, for the sake of argument, I create a 2 of 3 using the same HWW (a Jade) for all the keystores. Then I decide to change the brand of wallet for one of the keystores (say seedsigner), would that alter the wallet in a way that would change the foundations of the multisig so that the address are different, or that the descriptor would no longer correspond with the new setup? I've read that the order of adding the xpubs from the HWWs can. That's why I ask.

Second: I have read, but it wasn't explained why, that saving 2 copies of one of the seeds in a 2-of-3 setup can reduce security. Is this true? I don't see why that would that be any different than a 2-of-4 setup.

thanks.

Edit: I miswrote the word passkey instead of keystore. Sorry for the confusion. I had just read an article about passkeys. When Sparrow requests each HWW's information to be registered for mutlsig usage, it refers to it as a keystore. To clarify my question, if I register each keystore/seed using a Jade, but then later choose to change one of the keystores to another HWW brand (using the same seed), will that alter the setup in any way due to the brand change?