DRAG DROP You create a data model in Power BI. Report developers and users provide feedback that the data model is too complex. The model contains the following tables. 
Sales_Region and Region_Manager (right join, as new query) → merge in Manager (inner join) → finally Sales_Region and Sales_Manager (inner join). The right join at the start keeps only managers linked to regions. I think that's what the question needs, but always find these denormalize steps a bit tricky to follow. Anyone see a reason for different order?
