Change of health cover from E106?

We moved to France a couple of years ago and were covered by the E106 form for health cover and we were both issued with a carte vitale with its own number on it however my husband has recently started a business under the auto-entrepreneur scheme so cover has moved from CPAM to Mutuelle de Sud. I am not working so have cover through his business.

I recently went into a chemist to check that both card vitales we working OK as we had an attestation through the post from mutuelle de sud which had both our names on so I thought so far so good, however my husbands card was working but not mine and it seems as I am not working I am covered through him. But this means the number I was issued originally by CPAM is no longer valid. Therefore I sent an email to RSI and asked them to send me a new carte vitale but their answer to my husband was”

Afin d’obtenir la Carte Vitale de votre épouse, nous devons dans un premier temps obtenir un rattachement informatique au numéro INSEE national. Vous voudrez bien nous faire parvenir un extrait de naissance de votre épouse, où figure le nom de ses parents, traduit en français.

I am a bit confused as to what I need to do, it appears they want a copy of my birth certificate translating, but I am not sure why, it doesn’t seem relevent and I am not sure who I need to contact now to sort this out.