So I am not a registered employee in France. (When renewing my visiteur status each year, I declare that I do not carry out professional activity in France.)
I have both active and passive income from outside France. In previous renewals, I provided proof of my income sources. However, in most cases, I renewed mainly by showing bank statements with savings roughly equivalent to 12 months of the French minimum wage
But if you work remotely then you are carrying out professional activities here as you are physically in France.
Your call of course, but if URSSAF notice then you may have a difficult time. And I know there are very different opinions about the legal basis so not going to argue it here again.
I don’t either. Did she request one through ANEF? France is one of the few (perhaps only ) EU country that simply has no requirement for registration of EU citizens. If you meet the FOM conditions, nothing to do. I’m US/IT dual and I have had no contact with a prefecture (for myself, though I did get an EU family CdS issued for my late wife). I’m retired so can’t help much with the employment matters you have. But , to answer your actual question, I think it is very likely that you will get the same term CdS that she is going to get, unless you can make a case to them for why it should be longer. The way the passage in the law reads is that it is for the same length of time as for the EU citizen, to a max of 5 years. So, they don’t start out with a 5 year presumption and cut it down, they start with a year and give you more time if justified.
Yes, a bit naughty to be working without a French contract and not paying French taxes I assume.
I hope they at least submit tax returns declare the income! Then they are staying in the grey area of legality. Mind you there was that case against an American couple who thought keeping private health insurance meant they didn’t need to pay social security contributions. They lost.
I will also discuss these matters with a tax advisor and a lawyer. From my understanding, due to the double taxation agreement, some income earned from my home country is not taxed again in France.
Also, having sufficient passive income seems to be enough to maintain my visiteur status, since I have renewed it every year without issues so far. Right now, my main concern is the change of my residence status, and honestly I’m not sure how the process will end 
Even in that case, it must be declared in France, even if it doesn’t incur a tax liability in France.
Hi @kaxim
The declaration to France of your Worldwide Income enables France to see your Total Income and whether or not they would demand Tax over and above what you might have paid in whichever country they have an “agreement” with.
If you’ve already paid (in the other country) more than France would have demanded, France will not give you a refund 
but they won’t charge you.
There might well be social charges, that’s another aspect…