Hi from Paris,
I used twice Yad Vashem "page of testimony" to reach the author and share with him some informations about one of our "Losts".
Each time, I sent a letter with my own data (pictures & documents) explaining how we were connected to the same person.
Each time I got a positive reply with unknown pictures and documents, increasing our data on this person.
But It was always for our family use without any display on Internet (web site or FB or ...).
Even if your contact is a real person, I agree with our upper and previous detectives that we must be very carefull.
In France, we are very cautious and we have now an European regulation to protect privacy...
Archives and History of Medem Center - Arbeter Ring in France