  We consider a modification of gravity at large distances in a Brane Universe
which was discussed recently. In these models the modification of gravity at
large distances is ultimately connected to existence of negative tension
brane(s) and exponentially small tunneling factor. We discuss a general model
which interpolates between Bi-gravity model and GRS model. We also discuss the
possible mechanism of stabilization for negative tension branes in AdS
background. Finally we show that extra degrees of freedom of massive gravitons
do not lead to disastrous contradiction with General Relativity if the
stabilization condition $\int dy \sqrt{-G^{(5)}} (T^\mu_\mu-2T^5_5)=0$ is
implemented.
