Contracts

I have one parent company with multiple companies. Now I want to create one contract for parent company and sub contracts for individual companies. How can I do that?

I am giving the scenario below:

1. Contract for ABC Inc.

          1.a. Contract for ABC (Dhaka)

          1.b. Contract for ABC (Chittagong)

          1.c. Contract for ABC (Khulna)

The total amount will be calculated for parent company.