I never seen any reference to anything TG-metablob related before. If it's just extra planets and you want to add only horizontal stratas and such to them then, setting each displacement shader as a child to a surface layer, or distribution shader, should then give you the option to control what normal the displacements work from.
Maybe not, I really don't know what you're talking about!
I think it's that this arch is made from lots of different planet nodes, at least 6 of them, as far as I can see.