different Subtotal at drill up and down level

How can I implement conditional aggregation in Power BI to generate different subtotals based on different drill-down levels within a matrix visual? For Example,
suppose I have sales data categorized by 'Region' and 'Country.'

When drilling down from 'Region' to 'Country,'
I want the subtotal to include only sales from specific 'Countries' in a particular 'Region.'
However, when viewing the total at the 'Region' level, it should display the overall subtotal for all 'Countries' in that 'Region.'

Is there a method, possibly using DAX measures or any other approach in Power BI, to achieve this varying subtotal display based on different drill-down levels?"


example 
when all expand drill

region
India    Usa sub total
10        30      40

when drill up 
region 
40 

this is how things will look like but i need that when it is drill up which is region only it should show different value based on cond 
let say 50 

so it should be 50 not 40