multispecialty clinic

I work for a large multi specialty clinic. We have been having a lot of trouble with our postoperative global billing.. BCBS doesn't recognize the multiple specialties and considers all our providers of the same specialty because of our tax ID. This has caused numerous denials. Whats the best modifier to use. The 24 modifier relates to the "same physician" or physicians of the same of similar specialty within a clinic practice. But they are not the same specialty as their NPI show. This even affects our physcians seeing patient at the hospital. Any ideas? thanks, debj