I am working on a homebrew campaign setting and I am looking for some help regarding how best to approach the cosmology. I feel like fleshing out the planes, realms, and deities is a good place to start for a homebrew setting. I want to make sure that all these elements fit together well in order to create a sound foundation for the world in which my players will interact.
Here's my idea: I want to have a cosmology in which all the planes of existence are connected to one grand celestial tree, sort of like the old Norse/Germanic mythology surrounding the tree of life. I was thinking that the planes would simply "grow" and hang from the tree similar to how fruit would grow from a tree in nature. The only trouble with this is I want to use some of the deities and planes found in Greyhawk (like Pelor, the Abyss, Nine Hells, Elysium, etc).
Should I be concerned about doing this? I am kind of new to homebrewing so I don’t know what type of deity/realm lore might not fit with my “everything is on a tree” idea. And if this is a problem does anyone know how I might fix the outer planes mythos to better be attached to my tree?
Thanks a bunch in advance!