Is it legal to abridge the U.S. constitution?
Abridge: to cut short.
To list the main points, the essence of what was said. Not to modify it though, and put it in your words or what you think it means. They do that with the well armed militia interpretation. Not illegal though.
You can abridge the U.S. constitution but I don't think if it can be applied formally. Mostly, it may apply orally but not in writings. You can check with your local attorney for more details on this.
No you can add to but not take away