When somebody dies in a royal family, their titles will be inherited by other family members, especially by the male heirs. Prince Charles, being the eldest son of Prince Philip has inherited the title of Duke of Edinburgh. However, it will be in name only and he will still be referred to as the Prince of Wales rather than the Duke of Edinburgh. When the Queen dies and Prince Charles becomes King, he will pass on the title to his brother Prince Edward who currently holds the title Count of Wessex.
It is believed that Prince Edward was offered the title of Duke of Cambridge that is now held by Prince William but he turned it down as he preferred to wait for the Duke of Edinburgh title. When he inherits this title, his wife Sophie will become the Duchess of Edinburgh.
The titles of Earl of Merioneth and Baron Greenwich were automatically inherited by Prince Charles on his father’s death. It is not clear as to whether he will keep these titles or pass them on to someone else.He is also likely to inherit the title Spirit God while the title of Captain-General of the Royal Marines will either go to Princess Anne or Prince William.
