Our organization operates a web platform that hosts numerous newspaper properties. We recently acquired a new newspaper and are in the process of integrating it into our platform. As part of this transition, we’ve successfully transferred the App and App ID for the acquired newspaper into our Apple Developer portal. However, no Service ID associated with Sign in with Apple was included in the transfer.
Our current implementation uses a single, unified Service ID for all existing newspaper properties. This Service ID facilitates OAuth via a centralized Identity Server. The organization we acquired provided a CSV file containing a list of transport_ids, and based on our understanding, we’re expected to use the Apple endpoint: https://appleid.apple.com/auth/usermigrationinfo to initiate a registration process by submitting our Service ID (client_id) along with each transport ID. This step is required before users can sign in, and it should return the existing relay email address.
We have a few key concerns:
- Service ID Compatibility
- It appears that users cannot be transferred between Service IDs. In our case, there are now two:
a.) Our existing Service ID (used across all current newspaper properties)
b.) A separate Service ID previously associated with the acquired newspaper
3.) Due to architectural constraints, our platform cannot dynamically toggle between multiple Apple Service IDs. All properties authenticate through our unified Identity Server bound to our existing Service ID.
4.) Is it possible to call /usermigrationinfo using our existing Service ID rather than the one originally used by the acquired property?
5.) Relay Email and Apple ID Consistency
6.) We’re seeing conflicting information about whether the Apple relay email address (@privaterelay.appleid.com) and the Apple user ID are preserved during this migration. Some sources suggest that the relay email and Apple ID are tightly coupled to both the Service ID and Team ID.
7.) If we call /usermigrationinfo with our existing Service ID, will the same relay email be returned, or will Apple issue a new one?