To handle this scenario multiple document templates (one set of document templates per Company) have to be created. For example:
For ordering Goods:
Purchase Order / Sales Order for company A
Purchase Order / Sales Order for company B
Purchase Order / Sales Order for company C
...etc.
For receiving Goods and getting billed for those goods:
Purchase Bill / Receive on Consignment for company A
Purchase Bill / Receive on Consignment for company B
Purchase Bill / Receive on Consignment for company C
...etc.
For shipping and invoicing for those goods:
Sales Invoice / Ship on Consignment for company A
Sales Invoice / Ship on Consignment for company B
Sales Invoice / Ship on Consignment for company C
...etc
To create the document templates, click on the Menu > New Document Template:
Then, choose an abbreviation and a description accordingly:
The document templates (printouts) can be customizable entirely so that - for example - the Sales Invoice for company B will display the company info and logo of company B and so on. To customize the printout template, see here.