He was born Louis Doimi de Lupis, in 1939, later controversially added the names of Šubić, Zrinski and Frankopan under British Civil law and the title of Prince, having previously adopted the title of Count. While the Doimi de Lupis family were granted a knighthood by Emperor Franz Joseph I in 1855 and 1865, their right to use the names of several Croatian medieval noble families and the title of Prince (a royal title never held by any of the mentioned families, who were in Latin, Croatian, Hungarian and Italian historical documents styled as Counts of Bribir (Šubić), Counts of Zrin (Zrinski) and Counts of Krk (Frankopan) has been highly disputed. The Croatian Nobility Association expelled the Doimi de Lupis family from their membership calling the name reverting a falsification while John Kennedy, editor of directory of Europe's royalty and nobility Almanach de Gotha, stated that the use of the name Frankopan by Doimi de Lupis family is "more aspirational than inherited".
He married the former Ingrid Detter (born 1936), by whom he had three sons, Peter, Nicholas and Lawrence, and two daughters, Paola and Christina. His elder daughter married in 2006, the Lord Nicholas Charles Edward Jonathan Windsor (b 1970), second son of HRH The Duke of Kent, a cousin of the Queen.