Drew actually beat me to it. I was going to suggest a combination of cloning to create a USB. Then USBZTP on the new stack master. Then run clone.py slot all to sync all of the slots on the new stack to the master. Available in EXOS 22.2.
I do have a version of cloning, soon to be out, that will clone an entire stack from USB or across a network and is compatible with 22.2 and later.
FWIW, I've posted the clone.py doc to our EXOS applications github under an experimental directory, until the clone.py app download is available.
https://rawgit.com/extremenetworks/EXOS_Apps/master/experimental/clone/docs/clone.html