[Update: Following Walter's call with Shmuel Elhanan, we know there are errors in the original post, which I will leave to preserve the context for future posts. Yitzhak Rabinowitz did not change his name; his sons change theirs. Shulamit's family should be Rosenblum. Other spellings are in error.]
So after reading YES' will several times and reflecting that our family maybe held up his hopes in item 3 if having failed him in most of item 2, I began leafing through the other chapters of the book. Imagine my surprise in finding as the last item in the Holocaust section the text of the letter written by Shmuel's mother Shulamit Rabinowitz from Kovno on June 6, 1944 to her two older children just days or hours before she expected to perish along with her husband Yitzhak and eight-year-old son Shmuel.
This letter (and a shorter one that follows by Shmuel's father Yitzhak Elhanan Rabinowitz) is incredibly moving. She remains proud, though she is accepting of her likely fate. Her biggest regret is that Shmuel (whom she calls by the pet name Muka) will have his life cut short. Beyond that, rather than summarize I will let you read for yourself.
We know that in fact Shulamit, Yitzhak and Shmuel did not perish in Kovno. At this time, I do not know the full story of how they escaped and made their way to Palestine. I believe that Walter knows at least a short version of the story and perhaps he can fill us in. He may also follow up directly with Shmuel for more of the details.
What I do know based on Shmuel's 1996 correspondence with Morris Spector is that Yitzhak Elchonan (he later dropped the Rabinowitz name) died in Tel Aviv in 1992, Shulamit died in March 1996 in Haifa, and that Shmuel is alive and well in Rehovot at age 78 with his wife Zippora. They have two sons Benjamin and Ofra.
The two older sons to whom the letter was written both went to Israel as well. They were not in the United States when Shulamit wrote to them, but in Palestine. Benjamin was felled in the Israeli war of independence in 1948. Amos lived until 1965 and died in Tel Aviv of natural causes.
Here are the two documents, three pages by Shulamit and one page by Yitzhak. (Click to enlarge.)
By the way, Riemer's introduction to Shulamit's letter contains several errors. First, Shulamit became a Rabinowitz when she married Yitzhak, who was a great-grandson, not a grandson, of YES. Shulamit's last name was Rozenbloom before she married. When she mentions "your grandfather, grandmother and Aunt Jennie" in the letter, those are Rozenbloom family members.