Princess Charlotte might not be able to keep her royal titles. Due to a specific monarchy rule regarding Prince George, Prince William's only daughter is at risk of not being able to use the honor. MORE: Follow Wonderwall on MSN for more top news MEGA The rule that risks Charlotte's title According to protocol, when William becomes king of England, George will likely assume the title of Prince of Wales. This honor has been held by the father of three and King Charles III. However, this will spell trouble for Charlotte.