Biomes in the Nether and the End

I am making an update to a mod and I want to make a biome in the Nether, but i can't. I just wish there was a way to make boimes spawn in other dimensions. Here's how it works, you can select a dimension, like the nether but there won't be an option to have lakes or reeds or base height / variation. For the End, all the options stay the same.