Adopting an adult child

Hello, we could do with advice on how it would be possible for my husband to adopt my 23 year old daughter. We are British and all live in France full time.
Our daughter is profoundly disabled and my husband and I have an habilitation familialefor her.
I am quite concerned about what would happen if I die first and my husband would currently have no legal rights to make decisions for her.
Is it at all possible for him to adopt her, considering she is unable to consent (hence the habilitation familiale)
We have been told yes and no, but need a definitive answer.
If it is no, would this change if he applied for and was granted French nationality ?

I was told that adoption of adults isn’t recognised in UK law (Scottish and English) but it certainly is in France, it might be a lot easier for you though were you all to be French. I don’t know if foreigners can adopt someone here, if it isn’t recognised by their competent state.

Is this sort of thing something which a Notaire (or similar) might be able to advise ???

There seems to be a difference of opinion on it.

Here is a summary of the process Adoption de l'enfant majeur de l'époux, du partenaire de Pacs ou du concubin | Service-Public.fr

but unfortunately it doesn’t make explicit any nationality requirement.

Someone else here may know whether it’s possible (I assume the child’s mother is dead or agrees); in any event, if it’s possible you’d need to see a notaire.

Bon courage!

Hi, I am her mother and I agree. I suspect my ex husband might even agree. He has made no contact with her since she was a baby.
I am worried about what will happen to her if I die first. My husband has been her dad since she was 1 year old.

Apologies - I read carelessly! I meant the other parent so, as you say, your ex-husband.