Idea of plugin NEM Blockchain to existing system

Good day,
I can see NEM technology can be applied in the existing system but how it suppose to do it?
Let say, I have a running application that interacts with several databases. How to transform the whole thing by using blockchain to handle transactions such as to request without major modification of the existing system linked with an active database?

Hi. For what you want use blockchain in your system? What use case? I hope it’s not for replacing database.