If you can try, you can add a preset to your character and make it have Invisible Wings by choosing any wings and the preset on the same character, other then that, there is no way anything new can be added because the creator of the game actually left with the source code needed to do anything such as models, new Items, Mass Markings and any other major updates, even bug fixes, the only other way is if someone knows coding as good as their name, I'm sorry, but other then that, it cannot be done D-:
