Contact for more than one client

I saw a post on this that was closed but what I’m looking for wasn’t exactly what that post was about. I know I can associate a contact from a different client across tickets, billing, etc but I need the ability to actually associate a contact in the contact list for more than one client. Sometimes I’ll have a manager/approver for more than one of my clients. I’m going to use plus-addressing for now but just be nice to simply select multiple clients at the time of contact creation.