Unless you need to persist this data across sessions, you don't need to store it in a database table. From the perspective of Object Oriented design, why not make an object, and therefore class, that represents the structure you need. Something like this:
public class Relationship
{
public string Name { get; set; }
public string Parent { get; set; }
public string Child { get; set; }
public bool Allowed { get; set; }
}
Note of course that I'm using strings where you might want to use further objects of their own 'type'. Additionally, keep in mind access, and what should and shouldn't be allowed to access these properties... This is example is intentionally simple at this point!