J'y suis... j'y reste (1954)

Just as she is about to marry Jules, Nénette realizes that an adventuress has borrowed her identity in order to marry Hubert de Mont-Vermeil. But at the same time, a cardinal arrives, and the truth must be kept from him. Nénette passes for Hubert's wife, and the cardinal spends his time reconciling the pseudo-spouses. After many misunderstandings, Hubert and Nénette discover that they love each other, while Jules marries the pretty soubrette, not without first inoculating Hubert's virtuous aunt with his taste for racing.