Isobaric-isothermal ensemble with degeneracy

I've been studying statistical mechanics for a while, the topic is very far from what I've learned till now so my questions may be superficial. When trying to see what my entropy is in an isobaric-isothermal ensemble, which turns out to be applicable in reactive systems, if I write my partition function $\Delta$ without the degeneracy factor $\Omega$, the answer I get from


$$S = \sum p\_i\ln p\_i$$


is


$$G = -T\ln\Delta$$


(with $T$ in energy units, $k\_\mathrm{B} = 1$). However, if I take my systems to be in favor of a state or degenerate, I get


$$G + T\ln\Omega = -T\ln\Delta$$


Anywhere I read about this ensemble, the relationship for $G$ is in the first form and not the second, can someone give hints to some reading for what I'm missing here?


