Does "they younger" have any meaning in your family? Like "Charles the junior"?
36)One of the German painters of international fame was Hans Holbein the Younger. He adopted the principles of the Venetian school. When *the Reformation began, he went to England, carrying with him a letter of recommendation from Erasmus to Sir Thomas More, author of Utopia. He became court painter to Henry VIII and made portraits of the king...
William Pitt, 1st Earl of Chatham - Wikipedia, the free encyclopedia
This Prime Minister is also known as "Pitt the Elder," while his son, also a Prime Minister was "Pitt the Younger."
This use seems to be only in special cases where the father and son are both famous and there is a need to distinguish between them. I don't think it is much used today, though I have read people jokingly refer to US Presidents Bush the Elder and Bush the Younger.