Blockchain as a service (BaaS), as defined in [ITU-T Y.3530], typically includes consumers, providers and developers. A BaaS platform serves as the operational framework, offering resources and functionalities to create and operate blockchain networks, as well as to develop decentralized applications (dApps). In a typical blockchain network, node operators represent different stakeholders, each using their proprietary resources, to create and operate their blockchain nodes. These proprietary resources may come from various different BaaS platforms. When multiple BaaS platforms contribute to a single blockchain network, they must securely and reliably exchange essential information — such as the genesis block, organizational data, existing block records, and security details. This Recommendation presents a blockchain-enabled collaboration service (BCS) for multiple BaaS platforms. This service enables secure and efficient exchange of information across BaaS platforms, enabling the creation and operation of blockchain networks across the platforms, as well as the development of dApps. This Recommendation also identifies associated security risks and threats, specifies the security requirements and framework, and outlines the relevant security capabilities of the collaboration service.