How does your "Fact" expression look like?
You would need to rewrite this expression in your aggr() if you want to multiply each line fact value with the factor, then sum it up, e.g. for an assumed Sum(FactField):
=Sum( Aggr( Sum(FactField) * factor2, Region, manager))
edit: and maybe you don't need the aggr() function, but this depends on your data model.
As always, context (here: details of your application) is key to a solution!