Creation of New Subsidiaries and Joint Venture

 Dear Experts,

  Please guide me how to do this.

We had already a company setup in r12, say ABC Public Limited Co. (Parent Company)

This company has 100 Subsidiary companies and 50 Joint venture companies (50:50) ratio.

Now the management wants to bring all these 100 Subsidiary companies and Joint Venture companies into ERP. These are different companies having there own Legal status and Tax registration number (TAN).

How can I achieve this.

1. Should these be opened as separate legal entities or operating units under the ABC Public limited Co (i.e. Parent Company, which was already in ERP). 

2. These 150 Companies are being managed by the employees of ABC public Limited co. i,.e. parent company only. Will these increase the number of responsibilities in there user id.