Biome generation conditions

I would like to be able to specify additional conditions for where, when, and how a specific biome can generate. It would be helpful in many cases. For my example, I have a dimension with end generation. My idea is to make the main island of this generation be specifically EndBarren. Problem with that is, without additional generation conditions for biomes, the other biome I have, EtherMountains, can generate on that main island.