I've added this to my dating site, specifically to allow couple and family profiles to link to individual profiles as well, or for polyamorous people to link to their current partners while they meet others. It works perfectly, and just what I needed.
If you are an owner of a social network, you need this for sure, you can even add new relationships if needed... I like it ! it's easy to use and works perfectly !
This is a very basic plugin required for any social networking website. Facebook already has this feature. If you want to become atleast anything close to it, you need this plugin.