I have a good relationship with my dentist. I was his first patient when he opened his office years ago, and my family members are also patients. This shop is bonused here, by the way. My dentist's office manager is his wife. They're on board with me counting their freebies.
The W-9 only has to be completed by the dentist's office in order for them to get paid the coop fee. The dentist can opt out of being paid, if they choose.