Changement de statut pour une carte vie privée familiale

 I am a South African PACS partner of a Frenchman (we joined PACS before my arrival). I arrived in France with a VLS-TS VISA. My visa expires on March 21, 2022, and we are awaiting confirmation of our appointment for a change of status and obtaining a family private life residence permit. We do not have an answer yet and would like to know what can happen if the appointment is obtained after the expiry of the VISA? 
We have all the documents ready (including proof of a year of living together). 

Thank you for your answers, 
Iman