How do i create a member formula to pull for children as well

I would like to create a scenario member with a member formula that will calculate the variance between two columns in my management report. Then when I drill into the, for example, "Total Workforce Comp" it will show the variance of the children beneath it. How can I accomplish this?

a subvar that will update every year minus actual. but it doesn't seem to be working

([&CurrYrBudScn])-(Actual)