There was a much later Ferdinand Maximilien Mériadec de Rohan, Archbishop of Bordeaux, who died in 1813. He actually had a mistress who was an illegitimate daughter of Prince Charles Stuart, or "Bonnie Prince Charlie". They even had three children, who were kept secret and remained unknown until the 20th century.
Just to go off on another tangent, Donizetti wrote an opera "Maria di Rohan" (Mary of Rohan) based on a real person from the 17th century. It's actually one of his finest.