How to organize dataflows selection in Power Query by parameter

Hello everyone

Kindly asking for an idea/direction or maybe there is a solution exists already

I've got next situation: 
- report template
- a list of clients, who uses this report, it's the same for all of them
- for each client there is his own Dataflow as a source (with a number of queries in PBI service)

Question:
How to find a solution (I see it's a parameter), so we could choose a client in PBIX Power Query area (somewhere, somehow), and it would dinamically change a link in to chosen client's Dataflow in queries in PBIX? And then just Apply and Upload changes.

Please see a schema attached.

Any help will be highly appreciated
Thanks a lot