Hi,

you can read openerp documentation for multi company to know if it is what you need, see :

http://doc.openerp.com/v6.1/book/multi/index.html

Hope this will help and works.

Bye

Now, in Enterprise version 11. You can create multiple routes for your multiple companies. I also set up the same scenario where Company A will purchase Product A from Company B and Company B will manufacture it with MTO.

To set up this thing you can activate intercompany rules in Company form, inter-company tab. (Please note this feature is only available in Enterprise edition). This set up creates automatic Purchase Order/Sales Order for a Company B if you are creating Sales Order/ Purchase Order from Company A and selecting Company B as a partner.

After this set up you can set up you can set up multiple routes. I create following routes for each company

1. Buy for Company A

2. Buy for Company B

3. Manufacture for Company A

4. Manufacture for Company B

Setup you product and try creating Orders....!!

Done..!!!

Regarding stock you would just have to define a separate shop/warehouse/locations for each company This thread will help you with that:

http://help.openerp.com/question/16353/how-to-setup-multi-company-configuration-in-openerp-70/

As for separate procurement I also had this issue and managed to solve it with a simple script that I've whipped up in 5 minutes (hence it might not be that stable)

https://github.com/WizKeeD/shop_default_procurement

It is only partially tested on version 7, if I can help out a bit more with it please let me know

Good luck!

There is a new module that you can use to create a workflow for multi-company PO and SOs.

http://www.openerp.net.cn/new-intercompany-process-module/

To achieve this, the trick is on the property for each company i.e on the settings>parameters>configuration parameters. For each company make sure that you have defined it Income/Expense accounts property, Receivable and Payable accounts property etc. Then on the product do not set the Income/Expense accounts. Make sure that also on the Product category you have not defined the income and expense accounts. 

When you switch from company A to company B, openerp automatically selects the correct income/expense accounts using the property defined for that company. Properties are defined in the model ir.property. Remember to also define properties for ir.sequences. Hope this helps.