I have never done that myself but I certainly don't see why you couldn't.
HBH is known to encourage robbing so I would make certain my equipment was pretty bee tight before I attempted adding HBH to the recipe and make certain your entrance reducer are in place before placing on the fondant
if you don't mind perhaps post your recipe for fondant here for everyone to review. inverted sugar/fondant in a candy board is about the best means of feeding bees hands down.
This is not my recipe and I have not tried it.
8 cups sugar, 2 cups water, This recipe called for 1/2 teaspoon white vinegar.
Put all in sauce pan and bring to boil. Cover and boil for 5 miutes. Boil until it reaches 234 degrees. Remove from heat and cool to 200 degrees. Mix with electric mixer until mixture begins to turn white with air bubbles throughout. Pour into molds ( aluminum pie pans) and alllow to cool undisturbed. Store in dry place ( freezer).
I was going to add the HBH after it cooked and mix it in with the mixer. If anyone tries it before I do, let us know.
One thing, you might want to check, It seems that 200 degrees may be too hot to add HBH to the mixture, as it will evaporate . Seems I heard that, tho I hear things these days no one else seems to hear !
I think you are right. On one of the other forums, I read the flash point of one of the oils is around 150 degrees, so once it is below about 120 and is still workable, I think it would be the time to add the teaspoon to each quart. I also am concerned about robbing, as mentioned above by Tecumseh, as every yellow jacket, wasp and other sugar loving creature hovers around my hives when I feed syrup with HBH.