2x2 Enormous Trees Biome Creator

When i want to create a biome i get this box that says vanilla trees, and then i can switch between some trees. But i wonder if you can build a 2x2 stem when you select custom trees. I would appriciate that so much, but can you switch from 1x1 trees to 2x2 trees? Because the biome look kinda ugly with 1 block width and like 30 blocks tall, so please help me! Don't hurry, i just want it fixed