AP Advance Payment and Later it's Adjustment

Dear All

We are using PSFSCM 9.2 PT 8.53 with zero image. Kindly note we don't have any ambiguity with how the AP Advance payment functionality of PSFSCM works what's the methodology and how it works. Our query is a business need as against the system delivered process. Once, again would like to state that we know how the AP Advance functionality works and how to adjust once the advance is given.

So now to our query, kindly take a look at the following screenshots:

Now to the situation: Kindly read the Voucher Style in above screenshot as Prepaid Voucher; so the business situation is that we pay a prepay voucher to a supplier and deduct the appropriate  WHT (our WHT recording style is when voucher is posted the due WHT are recorded  by system). So continuing with the scenario the R/U Services - 153(1)(b)/4 10% and SRV on Sales Tax 20131, 20% (Payment 2 and Payment 3) are the WHT deducting at time of prepayment to vendor.