...
If joint account holders’ Account Operating Authority allows either [1] account holder to access account information and/or authorise payments without the approval of the other, then that same authority will apply to open banking account information and/or payments initiation scenarios. Either account holder will be able to provide the approval to their Bank to act without the need of approval from the other.
Note: [1] A joint account can have more than two account holders. For simplicity, this document is written as if there are only two joint account holders in the scenario. All of the principles would apply in the same way if there were more than two joint account holders.
...