Form W-8BEN-E

Hi!
I am the Principal Participant of a Private Foundation in Australia.

The Private Foundation provides service to a business in the US.
The Private Foundation and the American Business collaborate in a project (online product sales), and the Private Foundation receives around 50% of the revenue of the sales.
The revenue of the sales goes to my business partner in the US first (because I couldn't find a way to split the payout in the payment gateway), then the foundation sends her an invoice charging the adequate percentage from the revenue.

The Private Foundation is nonprofit and tax-exempt in Australia.

It is my understanding that I need to fill up Form W-8BEN-E, so my business partner in the US doesn't need to pay tax on the Foundation's share of the revenue, but only on her part of the income.

I need some advice on:
- if I filled up the form correctly
- if there's anything else I should do to avoid her paying tax on top of the Foundation's part of the income.

Is this something you can help me with?