How do they do that? Well, honor among thieves is a part. But mainly the first check doesn’t get cut until the kickback deal/check is already in the works. If the kickback doesn’t come thru then payment gets stopped on the big one. Bidum can explain it to you. Just get an appropriate prosecutor fired. Just happened in the Virgin Islands.
The party receiving the larger check uses mark-to-market accounting and spends that money as if it is already booked (loans, future proejct funds, etc.)
See “Enron, 2001”.