Interoperability is the key issue in NCW. However, old-fashioned weapon systems have low level interoperability. The representative example is BTCS. Therefore, we apply KVMF R1 to BTCS in order to improve interoperability and testify the effectiveness of how to apply without any changes in existing software. In this paper, we have proposed a message and software architecture design method for applying KVMF to developed weapon system. Finally, it is confirmed that the proposed method is superior to apply KVMF to existing weapon system in a point of verifying how to highly efficiently apply KVMF on existing weapon system.