Given Dataset + Report - how to split - best practice?

Hi. It's a very good idea to keep a single datasets with a good data modeling to fill many reports live connected there. If you want to migrate the sheets from the original file you can just copy past from two PBI Desktop files. Open the original dataset with many sheets and open a blank one. Create a live connection to power bi dataset on service with the blank one.

Then you can just open the sheet you want to migrate, select all components (like ctrl + A), copy and paste it on the blank one with live connection. Everything should be there. That way you can delete sheets from the original and create reports connected to a single dataset without replicating the dataset on each publish.

I hope that make sense