Well, I've phoned the family in Amsterdam and got a very old lady on the phone. She didn't mind I wanted to ask her something and explained the case to her.
She interupted me in my story, I had to talk very slowy, and said she knew the name Olga Alexandrovna Arsenieff. She mentioned directly the name Villa Ribaupierre.
And then......

:-/

the connection broke down

. I tried to call her back but she didn't answer. I could really cry.
The phone book said S. van Zutphen van Arkel. The lady I talked to could be the one mentioned in the death announcement.
I will try to call her back tomorrow, I have to consider the lady is very old and I don't want to bother her. Otherwise I shall write to her.
Lucien, I really think we have something here.
Anna