The first two suggestions actually would work, either you make use of one wallet and the multiple addresses there or you make use of two or more wallet. This is easily achievable by using a single seed phrase and adding different passphrases to each one to make them new and different wallets. Since you mentioned multisig using this passphrase will be a little more complicated because you might have to get a coresponding multi sig set for that too which will seem way to complicated to me