How to include creditable withholding tax (cwt) on sales return (RMA)?

Good day!

I would like to ask how I can include cwt on the sales return total due computation. Right now, we have a cwt on sales orders created and when execute a full sales return, the total balance due of the sales return is bigger than the invoice since the cwt computed in the invoice is not being included in the sales return.

I hope I have explained this clearly. Thank you.

Edit: We removed the Reference field through a trigger before we booked the sales return as our goal is that the sales return will not automatically offset it's reference invoice. I removed the trigger and the sales return is now equal to it's original invoice. Is there a way where in the sales return will still include the computation of cwt even though the Reference field is blank?