BCBS (primary insurance co) requires bilateral services (i.e. 31276) be billed on two seperate lines utilizing modifier -50 on one claim line:

31276 unit 1
31276-50 unit 1

Tricare (secondary insurance co) requires bilateral services be billed on a SINGLE line with 2 units and no modifier:

31276 unit 2

I billed per BCBS guidelines as primary payor and Tricare paid for one side and denied one side of the bilateral service for "Procedure code is inconsistent with the modifier used". They will not budge on this and say they will not pay the second side services on the claim as filed.

How can I file the secondary claim to Tricare to get the payment we are due without crossing any legal lines? I don't know if I am legally able to modify my original claim.