Price procedure if price condition amount is final and 2 taxes are included

My problem is the customer uses an interface that sends the price with the tax amount included and there are 2 tax conditions involved.

If the material only has one tax indicator the amount is correct.

But there are cases where both taxes apply, so the formula needs to be different when both taxes apply.

I was looking at standard price procedure POS100 and they use a statistic condition for each tax and they use some formulas but so far I do not know how to suppress the tax amount depending if only one or both taxes apply.

If anyone can share some advice would be appreciated.

Regards,

Carlos