Add a column to matrix

Hi!
I have been following your advance matrix video but what if we want to add a additional columns in an Matrix visual like if the in my matrix I have groups the days from (0-30 days,31 -60 days so on) the addition of (overdues) appears at last but I just wanna add a column to it call (not due) and finally want to add the both (Overdues and Not due ) column into a (Total Receivable column) all measures are been evaluated I just want to add this 2 (Not due and total receivable to Matrix visual what I have made) Hope you got what I'm trying to explain. I'm preparing a Receivable Dashboard.