A subcontract requires the sub to name the prime contractor and owner as ADDITIONAL INSUREDS on the sub's commercial general liability policy AND to provide a WAIVER OF SUBROGATION. The PRIMARY purpose of the waiver of subrogation is to:

Explanation

A waiver of subrogation stops the sub's carrier, once it has paid a covered loss, from standing in its insured's shoes and suing the prime to recover what it paid. It does not change how much insurance is available — that is what the limits and additional-insured status do. It does not touch the indemnity clause, which is a contractual duty that survives regardless of what the carrier pays. And it says nothing about whose policy responds first; that is the primary and non-contributory wording.