I haven’t tried adding on npubs for shared access, but I don’t think you’d need to reapprove them. As long as you have access to the nsec.app dashboard you should be able to add new npubs to the connection if my understanding is correct. You’re adding the permanent user npubs, not the temporary ones. 

 You would need to approve them for each app though 

 Actually I’m getting mixed up. I think you’re right. Probably should wait for confirmation from @brugeman though.