If I am understanding the code correctly, it looks like the Oven inherits recipes from the Furnace. This works most of the time, but if the recipe is only available in the Smoker or Campfire (e.g. Farmer's Delight's Smoked Ham) it does not work in the Oven. I don't know how feasible it would be to inherit from all the possible sources at once (Smoker/Campfire/Furnace) as I imagine there would have to be extra code for duplicates, but if there was a config option to determine which handler the Oven inherits recipes from, that would probably work fine for my purposes as a pack developer.
Thanks!