Intercompany setup

In Axapta, I have 1 parent company with 6 different companies according to the products they sell. I would like to setup one master table for displaying all customers so that the individual companies may view this table. In each of the individual installation of Axapta for each company, I would like to let them select a customer from this master table to their individual customer table. If a customer does not exist in the master table, the company can add this new customer to his customer table and the master table. Please advise me on how I can go about it. How can I go about the use of a virtual company setup?