Plant determination in CRM sales order by Sales Area

Hi Gurus,

I have two problems with the partner determination in Sales Order.

Now we have a partner procedure determination with an access sequence CRM_PROD_SALES_A.

But in our case the Vendor (plant) should be determined by sales area.

First we need to assign the plants to a sales area, but we don't have this option in SAP CRM in the BP transaction. Is there an option in the CRM to assign a Plant to a several Sales Areas?

Next, we need to determine automatically the Plant in the document (sales order), obviously the determination must be with a sales area-->plant.

The determination is at item level.

Thanks for your suggestions.

Maricarmen