This.

So you would still need to make an (or some) onchain transaction(s) from the seed wallet to use the seed + passphrase wallet.

you can use a passphrase with your old seed. This will create a complete new wallet which you can only access/restore if you have the seed and the used passphrase.

megaptera

I've a hardware wallet already set up, is it possible to add a passphrase to my old seeds?

bitcoin_beginners

Hello, 

I've a basic question...

I've a hardware wallet already set up, is it possible to add a passphrase to my old seeds?
I know this would create a new wallet.

Thanks 