Option to connect a contact to a profile

Hi.
so, i hope this is the right place and has not been discussed yet, i wasn't able to find anthing...

Is your feature request related to a problem? Please describe.
Today i tried crating some circles with family members and it worked quite well :)
Then i stumbled upon a quite unnecessary circumstance. I can add to a circle (or also, in hindsight that also happened sometimes when i shared files or sth. else with someone) either the Nextcloud-User "Brother1" or i can add his contact, if it has a e-mail-address attached to it. So in one case i share some folder or my calendar with another NC-User to see when he logs in or i share it with some guy with a e-mail-address.

Describe the solution you'd like
I would like to be able to associate other Userprofiles with the contact details i have in my addressbook as i like. For example i want to connect the NC-User Brother1 with the contact i have in my address book including his e-mail, phone and what else.

No files, tests, or entry points are identified in the issue; start by locating how Nextcloud users and address-book contacts are represented and how circles or sharing select recipients. Done should allow a user to associate a Nextcloud profile with an existing contact and use that association when sharing or adding circle members.