Ok then Phil your question was a bit ambiguous. Maybe better to wait until she actually gets here as you both have to pass before some form of officialdom.
As for CDS’ as most prefectures are not processing requests and asking that applicants wait until after Brexit then you don’t have much option !
Perhaps we are all suffering with a touch of the sun.
Phew, know I am. (it’s 42c in the shade - I took a quick walk to the mairie and back and I am shattered)
LOL - no Stella - I LOVE the hot weather - bring it on 
Only 38C down here 
Let’s hope that Phillip is more ‘on the ball’ when it comes to questions that may be asked during his citizenship interview… 
38c - that’s nothing, believe me. Humidity seems high as well, for some reason, thus 42c resembling 100c in the shade… yikes 
@phillipcox I wonder - is PACS something that has just entered the conversation between you and your partner (??) and forgive my bluntness but have you discussed “marriage”. ??
Ressenti 43 ° here and everything is so quiet, even the frogs have given up 
! The cat is flopped under the table with no desire to put a whisker outside 
Hi…I like getting to the point…no problem…as I receive pension de reversion from my late wife, marriage would cancel this out, whereas PACs allows it to continue. We may well consider marriage at a later time though.
I only mention it since a French couple announced to me that they were getting married. We’ve known them for years and not known anything else. He explained that they were PACS’d and he had discovered that unless they were married his “partner” would not benefit from his pension rights (or whatever) if he died.
I know each situation is different. Our initial aim is to get her into the french system asap and I can do an attestation sur honeur to enable her to have an adress. She will apply for French citizenship eventually. Also its a question of health cover and CV. She will probably register as a micro-entreprise but almost all work will be in uk to start with
I only mention the marriage bit, for your information. 
I have no official information on this, but the way I look at it it seems that that would make absolutely no difference. To be eligible to apply to join the health service they require stable residence of 3months +, equally to start application for an (as yet unnecessary) carte de sejour.
Why should the fact that you are pacs’d, married, or bound together with bits of string make any difference?
I became resident a year after my partner (who is my husband), it never occurred to me to consider that this waived the 3 month rule. Each person’s application is considered in their own right.
I think it is only for non europeans wishing to join their partner currently resident here that it might provide extra security.