But you have to unlock it first to spend it and you lock it again for the recipient. You don’t really change the lock, you just move bitcoin behind a new lock.

I mean I’m not sure about all the technicals details here and am sure that there’s a reason why what I‘m thinking of won’t work.

But from what I heard it it possible using FROST to add and remove required signatures from a multisig without an onchain tx. (So changing the lock without unlocking it)