At the time of his birth he was registered with the name Mircea Grigore Carol Lambrino.

One of these situations was a letter published on the front page by the Romanian daily newspaper Epoca (17 January 1920).

Signed by Crown Prince Carol, the document is a statement in which the future king recognized his paternity of Princess Ioana's baby.

On 6 March 1957, the Portuguese ruling was recognised in France by an Exequatur of the Tribunal of the Grande Instance of Paris.

Carol's younger half-brother Michael appealed this ruling which was upheld by the Court of Cassation, 8 January 1963.