This is a very late reply lol, I haven't been back on mmd to try it cuz I've been busy with other projects but thank you so much and I would appreciate you explaining how to move stages(if you wouldn't mind) because there's a way to move the lights on the default stage that comes with the program and I don't know how.
If the stage is an .x file, you go to model manipulation and select camera/light/accessory. Then you got to the yellow box and click on 'load'. Find the folder with the stage and click on the .x file to load it. If the stage is a .pmd file, you just load it the same way you load a regular model. Hope this helps. ^_^