When I first got Ivan I gave him greenies all the time. I had to quit feeding them because they always make him sick...it just took my awhile to realize it was the greenies that were making him sick.
What kind of bones do you use? If your frenchies are anything like mine they are obsesive chewers.
mine are too. they love the bullysticks the best. for teeth cleaning i give them raw soup bones. the big ones that they could no way swallow. and milkbones. and once in a while if they have been good "kids", they get their favorite treats, cheez-its ( and no , they dont get their own box) lol
most of the farm/feed stores sell them along with several other goodies like pigs ears, etc. if you dont have one near you, you can order them online at places like dog.com or pet discount supply co.