Each wallet address contained inside your signal signature wallet is unique and thus the public key, that may have been exposed, has no bearing on your multi-signature setup. Especially since the derivation path is completely different and it is part of a multi-key setup. Obviously it's important to keep your multisig xpub private.
Even if that single signature seed phrase had been compromised, without your knowledge, making it part of a multi-sig protects your wallet, albeit not a perfect setup.
You can also get a little advanced and make your original single signature seed phrase have a passphrase as part of the multi-sig setup.
There's technically no problem in reusing it.
Each wallet address contained inside your signal signature wallet is unique and thus the public key, that may have been exposed, has no bearing on your multi-signature setup. Especially since the derivation path is completely different and it is part of a multi-key setup. Obviously it's important to keep your multisig xpub private.
Even if that single signature seed phrase had been compromised, without your knowledge, making it part of a multi-sig protects your wallet, albeit not a perfect setup.
You can also get a little advanced and make your original single signature seed phrase have a passphrase as part of the multi-sig setup.