How do you customise the commissions for a Network Partner?

Locate your Network Partner in your Client Management Tools as standard. Locate the "Payout" box within their client profile found at the bottom right of the page as shown below:

You can modify this data at any time, however, it will only reflect for future completed jobs and not any jobs already completed, even if payment/invoice is pending generation.

If you wish to raise invoices at a different rate to your client invoice generation date, use the standard tools found to the left of the page for Client Invoice generation as you would do a standard customer.