Not only Camille. Quite a few members of the family are illegitimate (or were born illegitmate), although several of the parents later married:
Alexandre
Jazmin
Camille
Louis Ducruet (born 3 years before his parents married)
Pauline Ducruet (born 14 months before her parents married)
Sacha Casiraghi (born 5 months before his parents wed)
Raphael Elmaleh (parents never wed)
Princess Charlotte (Rainier's mother)
Elizabeth-Anne de Massy (Rainier's niece, Princess Antoinette's daughter)
Christian de Massy (Rainier's nephew, Princess Antoinette's son)
Christina de Massy (Rainier's niece, Princess Antoinette's daughter)
With a list this long, the royal family should have plenty of experience managing children born outside marriages.
Alexandre
Jazmin
Camille
Louis Ducruet (born 3 years before his parents married)
Pauline Ducruet (born 14 months before her parents married)
Sacha Casiraghi (born 5 months before his parents wed)
Raphael Elmaleh (parents never wed)
Princess Charlotte (Rainier's mother)
Elizabeth-Anne de Massy (Rainier's niece, Princess Antoinette's daughter)
Christian de Massy (Rainier's nephew, Princess Antoinette's son)
Christina de Massy (Rainier's niece, Princess Antoinette's daughter)
With a list this long, the royal family should have plenty of experience managing children born outside marriages.