Customer A buy goods from me , and customer A need efaktur for his company PT ABC.

currently in my contact , i have company PT ABC , i set it's VAT number and it's Customer Code [ Customer Biasa , no 1] 

while in Customer A Contact , i set his company to PT ABC

i use pos module to create invoice , usually i select customer PT ABC , and it works

but i cannot track , which person buy goods from me because PT ABC has several people come to me , lets say Customer A , Customer B , Customer C

so i need to select Customer A to track when he come , and what he buy , meanwhile i need vat tax report [ efaktur ] addresed as PT ABC [ using invoice ] , and i can download it's efaktur xml so i can import it on tax apps

is that possible ? 

how to do it ? 

thanks