Sinus CPT® coding

Hi-
Sinus procedure code? The two procedures were Fontal balloon sinuplasty bilateral, and Maxillary antrostomy with balloon sinuplasty on Left.
I have 31296-50 for bilateral frontal, and not sure if the maxillary antrostomy is part of the process of going into the frontal sinus. I coded 31256-LT. Would it be correct to code both together?

hholty