Thanks Sukrut for your reply.
if customer paid prepayment and then he lends one of the two products.What is your Solution?
For example:
-First, he buys Product1(2000$) and Product2(3000$)
-Open Transaction is created with 3 installments like below and he pays 1000$ as prepayment:
-Now, he lends Product2.
How I create Open Transaction according to just Product1?