I suppose all four theoretically have supporters as claimants to the abolished throne of France.
A small detail: The surname of King Juan Carlos is simply de Borbón y Borbón, without Dos Sicilias. For example, note his mother's name in the
the royal decree of 1987.
2. Igual título y tratamiento recibirá la madre de Su Majestad el Rey, don Juan Carlos I de Borbón, Doña María de las Mercedes de Borbón y Orleans.
The name of Borbón-Dos Sicilias was taken up by Doña María de las Mercedes' half-brother, Infante Alfonso, and his issue, under his claim to the abolished throne of the Two Sicilies, but the other members of his family remained merely Borbóns.