PowerBI C# Editing source files paths in DataMashup file // Programatically changing datasets

Hello,

I want to automate changing source files paths in my report. I want to do this because I will be publishing the same report for many clients, each with different data set.

When I unzip .pbix file I can see that those paths are saved in the Data Mashup file in a readable form. However, when I change them and load .pbix file again I get an error that the report is corrupted.

I notice that there is some sort of header and footer that are not human-readable. I guess there is some kind of checksum there. Any idea what kind of checksum is there, and how can I edit that? 

Alternatively: is there an alternative so I can update dataset programmatically and maybe even upload it to separate Workspace?