Are you saying that wallet A & wallet B address is derived from one seed?
Yes, they are from one seed.
As Long There Is No Transaction Between Them, It Will be safe
If Your Wallet Use BIP32 (High Chance), Don't Share Your Master Public Key (or seed phrase)
BTW That Type Of Wallet Is Not Called Multisig
Oh, I see, now I know. I thought this is one they called Multi Signature Bitcoin wallet. Thanks that info!