how to PO service workaround

Hi expert,

I'm having difficulties regarding PO service transaction. The scenario as follows :

- Deal with vendor for specific work such amount IDR 126,500,000.

- Then, vendor issued invoice IDR. 42.000.000 (not based on QTY)

I have created PO :

a. QTY = 1

b. Unit Price IDR 126,500,000

my question is :

1. how to enter in product receipt menu ?because I use three way match.

2. remaining for next invoice should be IDR 126,500,000 - IDR 42.000.000 = IDR 84,500,000 

thank you for your advice