How to Track Outside Vendor Inventory Quantities?

Hi,

I just started with a company and I'm in charge of updating their quickbooks data and building out there inventory module.

We purchase raw materials from an overseas vendor (Company A) and have them shipped to a domestic partner's warehouse (Company B) for stocking purposes. In addition to the prepaid inventory on stock from Company A, our partner also has materials specifically reserved for us, but have not been paid for yet. 

So at Company B's facilities, we have a mix of products, some that have been paid for, and some that have not. We need to track inventory of all items and get real time updates whenever quantities change.

What is the best way to track this?