Implicit & Explicit Relationships
From Social Patterns
Most social networks require users to make explicit connections and declare their relationships publicly. But there are situations where the implied relationship will do. By subscribing to someone’s blog or joining an interest group there is an implied relationship between the user and the author of the blog or the person and the group of people involved in the group. The very nature of being involved in the group implies relationships that may or may not be very strong.
Expressing these implied relationships within the interface can help users make explicit connections as well as get a sense of the group they are involved with.
Allow users to become involved without having to explicitly declare relationships and allow them to be expressed as they evolve.