Wait.... N5? Wouldn't the new nest be N3?
Sassafrass - I believe it was explained like this, and I am sure someone will correct me if I am wrong.
Original nest
N0 was in the bluffs,
N1 is where the Y branch is located,
N2 is next to current nest and fell down,
N2B is current nest, so new nest would be
N5 for a total of 5 nests.