To find the bookings generated from any other 3rd party site do the following:
Go to Bookings > Guest Bookings
Optional: Enter dates in the Date Range field and select Date Mode: Departure (normally all bookings departed in the previous month)
Click on the Show/Hide more options link
Under Select User select the user (Stayz, HomeAway)
Select Pending and Confirmed from the Which Bookings filter
Click on Find Bookings
The list will display all Pending and Confirmed bookings that have been made from the 3rd party site. You can then click into the Edit > Pricing tab button for each booking to see the 3rd party commissions.
Repeat the process for each 3rd party site.