I used to have a similar situation arise with flight instruction (that wasn't my main line of work, I just did it on the side as a way to raise extra spending money). One individual would always get me to do free bi-annual flight reviews and the other got free instruction from me for his commercial license. These people weren't poor, they were just cheap. It would have been different if they'd have showed up to help me build my deck or paint the house, etc. but they never did. I finally came to realize that if they decided to end our friendship because I no longer gave in to their request for freebies then they weren't worth having as friends.
I like the idea of the 'friends and family special rate'. Let them know they're getting a good deal, and make sure they know how many hours of work are involved. You could put it like 'my normal rate for this would be XXX, but I'll knock YYY off of that as your wedding present'.