Regarding "RooAddPdf coefficients normalization"

if it’s not possible to obtain those coefficients normalized to the fit range, i was thinking to obtain the yelds in that range by integration
of the components of the model.

The problem is that i dont’ know how to do that
(if it’s not possible the natural question is why not ???)
and searching on the web doesn’t bring me any light …

Any help will be very appreciated !!

Many thanks,