Withholding Tax Amount Substitution in F110

Dear Experts,

We have a scenario where 1 vendor supplies 2 types of Invoices. 1 Type of invoice is subject to withholding and other one is not subject to withholding tax as per the law of country.

So, We wanted to substitute the tax amount, at the time of payment(via F110), of invoices which are not subject to withholding tax. However, we are not able to find any method how we can substitute.

Please advise how we can substitute the tax amount in F110 or any other method to achieve this requirement will really help us as the legal requirement is applicable from 01.01.2015.

Regards,

Vishal Ahuja

P.S.

1. We can not create a separate vendor because system does not allow to create 2 vendors with same VAT Number.

2. We know the method of substituting Tax base amount in MIRO itself but we don't want the tax base to be set to 0. We want only tax amount to be 0.