This vault concept is very interesting. I'm not sure I've ever seen an altcoin with something like that before (someone please feel free to correct me on this.)
Is there a deeper explanation of vaults anywhere? The website is kind of vague about this -- it says multiple keys, and talks about whitelists and resetting. But no more details than that.
I think cold storage is one of the least friendly things about crypto...
You can find more in the whitepaper - it doesnt get into the technical side as much , but it unpacks "how" very well.
Do a "Ctrl + F" (find) and scroll though. Let me know if you have any other questions.
https://www.merit.me/uploads/2018/whitepaper.pdf