Not sure if you'd want to do this.. The best practice if you plan on using the same merged data set would be to merge it outside of powerbi. Perhaps etl the data into an azure database table... Or better yet a managed data warehouse.
Power bi is great for mashing up data for reporting but it's not the right tool to use if you share data sets.
I'm thinking of using Excel [Power Query (2013) or Get & Transform (2016)] to do ETL, then using the Excel file as data source for Power BI. That way data is still accessible in format that can still be shared. However, further changes to data structure are not fed back into data model in Excel so it would be a bit clunky.
An export to Excel button appeared yesterday hidden under the three dots in the top right corner of the report beside the "pin" icon. this exports the current report data to excel. No blog post yet regarding this but there is also now a print dashboard feature as well.
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