Probably best way to do this is a Query Select field using CB Query Field that queries for all the users that user is connected to. This would display a dropdown of all their connections in profile edit. Otherwise a text field for them to supply a username should also work (you can validate the username exists using Query Validation from CB Query Field if necessary). You can also use the Connection Types feature within CB > Configuration > Connections and simply add Buddy to it. Then in connections management they can set that type for a user they're connected to.