Well... Somehow, I got a feeling, that Stiles is the only one who thinks, that Peter is a member of BH Pack and a Beta. The rest of the Pack and Peter himself are perfectly aware, that he is nothing more than an Omega, who's been allowed to join the Pack only formally, and nobody's ever even tryed to form pack bonds with him, Derek included.
Moreover, I'm starting to suspect, that Stiles himself, despite everything he did for the Pack, isn't considered by the wolves as a part of "them".
Scenting a pack member - it's an instinct, and when even the Alpha isn't inclined to do so, to mark a fragile human as "mine, hands off, bitches :)"...

It seems to me, that Peter and Stiles havn't formed "pack inside pack", they - two packless outsiders - formed their own brand new pack.

Renatta