I haven't found the article I was looking for, but I found another one:
Here he doesn't speak about Nicola, but he says the he had seen her in that shop, that he liked her so he decided to introduce himself.
If she was the sister of Nicola, he would have met her in another way.
He says also that Sonia was born and raised in Turin.
It's strange that her "brother" was born and raised 1000km far from her
