Q1 Can a user link more than one hardware device in Liminal Vaults?

No, Liminal supports only one hardware device per user.

Q2 What happens if a user loses their hardware device passphrase?

The users in an organisation must back up the passphrase and seed phrase of their hardware devices. Liminal doesn't have access to any of them. If a user loses their hardware device, they can import the seed phrase into a new device. If a user loses both seed phrase as well as hardware device, they need to set up and link a new hardware device within their organisation in Liminal Vaults. The other users associated with the multsig wallet need to create a new multisig wallet, add that user with new device, and move the funds to the new wallet.

Q3 What happens if the same seed phrase is imported into a new hardware device?

If same seed phrase is imported into a new hardware device, it will work without any changes (apart from granting browser permission to allow device to connect).