Peer-level connections

Relativity offers innumerable advantages over the built-in Drupal 'book' module, IMO. The ability to enforce child and parent node types is huge. The major downside, though, is the inability browse first/prev/next/last style among peers in a particular relationship.

This, combined with a new group of node properties first/prev/next/last ids and themable rendering functions, would allow the creation of very rich content hierarchies while overcoming a number of book's limitations. I'd like to take a stab at adding this to the module and, if it proves successful, offering the patch for inclusion. Are their any thoughts on the appropriateness of this addition?