Article 509 of the French Civil Code
The guardian may not, even with authorisation: 1° Perform acts which involve a gratuitous alienation of the property or rights of the protected person except as stated in relation to gifts, such as the remission of a debt, the gratuitous renunciation of an acquired right, the early renunciation of the action for reduction referred to in articles 929 to 930-5, the release of a mortgage or security without payment or…