Why do we need to know the person's nationality? They're clearly a "visa national", otherwise they wouldn't have had to apply for a visa. "Visa national" is all we need to know.

nbusin, just to confirm - your relative obtained her Schengen visa from the Italian embassy/consulate because at the time of application she was planning to visit Italy, or to visit a number of European countries starting in Italy. The original trip didn't happen, but she is now planning to visit France and her visa is still valid. Is that correct?

The rule is that one must apply for one's visa at the country that is the main destination OR the first point of entry if there is no main destination. (It was always an "either/or"). This rule is, primarily, about the application process - to spread the workload between the various embassies/consulates, and to stop people from flocking to embassies that are known to be a "soft touch".

Once a visa has been obtained it is valid for travel anywhere in the Schengen area, and if it's a multiple entry visa then I think it is understood and accepted that subsequent trips may be to different countries. You can't hold more than one Schengen visa at the same time, so if your relative is now planning to visit France then her existing visa is the one she will need to use.

Chances are they won't ask any question. If they do then should give an honest answer (i.e., she shouldn't lie about being on her way to Italy if she isn't). Tell the truth - "I was going to visit Italy last month but my trip got cancelled"