Sorry for the crash, but I think they probably researched NPC sororities and got help from another fraternity and chose the things they liked most about the other organizations. They obviously didn't read the GC threads about starting their own chapter
I am not sure if legally you can do anything, unless your motto is trademarked. I would be upset if they did it to Chi O so I don't blame you for being upset. Good luck and let us know what the outcome is.