Deep Connections Gramplet
The Deep Connections Gramplet will find a relationship between the home and active people, if one exists.
This can take some time, as it thoroughly searches through all relationships. Deep Connections doesn't provided named-relationships (such as, "great grand aunt"). Use the Relationship Calculator or the Display Preferences for that. The Deep Connections Gramplet gives you a chain of people that form a related connection between the Active Person and the Home Person.
(Eventually, the Deep Connections Gramplet will become a Tool. ??)
You can download this plugin by following the directions at Third-party Plugins.