Secondary insurance?

My primary insurance carrier does not cover the lap band, but my secondary does, which is what I planned on using. I plan on dropping my primary at open enrollment since I only kept it bc the last few times I tried to get on my hubbys ins, the hr dept kept 'losing' my dependency papers and I didn't want to be left with no ins. Will I be able to use my secondary ins for the surgery, I know they convert it and imcurrently onmy 3rd month med. Supervised diet. Has anyone used their secondary ins? Its bcbs il.