I have this very awkward situation with my mobile application developing team.
I have consulted dev team to implement the delay registration method for the app but happened to some miscommunications the team forgot to include that part of the code and now we are having duplication contacts in our Marketing Cloud instance because the subscriber keys we're using on our MC instance do not link to the device and we don't have any downstream data to our backend system.
To be honest, I did some research through every solutions and come up with 2 outcomes.
- We need to have out backend team get data from CRM first to backend for app developing team to lookup and update subscriber key for the app again.
- (New idea) We keep everything at it is and using API to update subscriber key accordingly device token we send over to MC earlier.
The 2nd idea seems not so realistic to me since I didn't see any documents or posts prefer to the solutions.