Combine two p2tr addresses into one

Question

Is it possible to combine two (or more) P2TR addresses into a single P2TR address spendable by the owner of any one of the input addresses? I.e. like a 1-of-N multisig. Something like making tapscript branches from tap trees?

Answer 1

Yes, since the spending conditions of a P2TR address are either to provide a signature for a public key or to satisfy any of the scripts in the script tree, the spending conditions of multiple P2TR addresses can be combined into a single one with a larger script tree (the key conditions can be simply represented as additional scripts). However, this can only be done by someone who knows the structure of the original P2TR addresses' script trees, as the addresses only encode the public keys. Likewise, after the conditions have been combined, the individual parties need to obtain and back up the structure of the resulting script tree in order to be able to use their spending conditions.