Thinking about multisigs and social recovery wallets.

Is it possible to have a more complex multisig where m of (n-1) can access the funds (I.e. in case the owner loses their key), but the nth key belongs to the owner (the master key) and can access the funds without anyone's permission?

Is it possible to generalise that further and assign weights to keys? I.e. the master key would have full weight to reproduce the above behaviour and other keys would have lower weights depending on how much the owner trusts the keyholder.