I would like to add a K2 User to a K2 Custom Field.

Example: in addition to attributing an Item to the author, there is also a photographer, who also has a K2 User profile.

I've been able to add a standard text custom field with the photographer's name, and I've been able to modify the template to display the photographer's name directly under the Author's name. But I'd like the custom field to link to the photographer's user profile similarly to the Author profile's link. There, the user would see a list of other items associated with the photographer as you'd see for an Author.

Here's where it gets even more difficult. I'd like the list of associated items to include both Items authored by the User and items where the User is in the custom field (i.e. Items for which he was the photographer).