From a brief look it seems that it might be possible with reflection. I'll point you in the appropriate direction. Each Biome a village spawns in has it's own area. For the Plains biome it's PlainsVillagePools In there is a static {} and an init, but init does nothing except make sure the static{} gets called.I've notified that all the parts including the part where entities spawning in structures is handled by the JigsawManager REGISTRY. It loads up nbt files from the data directory, use an NBT explorer to figure out the structure so you can create one for your Entity and then you'll have to somehow put it in the JigsawManager's registry entry.