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.