Here's one that has had me puzzled for a while but I hadn't delved into it until mentioning it to Harriet on the phone the other day. We've always known of Julius Rabinowitz's two children Abner and Judith, but the family's census records show that there was also an older son Seymour. Now that is odd, one, because we have not heard of him and, two, because Julius had a living brother Seymour and one would have thought that precluded him giving his son the same name.
In the past, when I saw Seymour listed on the family's 1930 census, I thought that perhaps that was brother Seymour Rabinowitz who might have been boarding with them. However, the age is not right since this new Seymour seems to have been born in 1903. Also, there is another 1930 census record with Seymour the truant officer living alone. That Seymour, Harriet's father, was born in 1887.
I had left that alone, but now I see that the younger Seymour is also listed on the Julius Rabinowitz household in 1920, when the elder Seymour is still residing with Lena and a couple of other siblings.
The census pages are shown below. In both cases, only some of the family members are shown since they are on the top lines of the form and the missing family members are on the previous page. I have checked that they are there so you can take my word.
Anyway, from this, I feel we have to conclude that Julius and Anna Rabinowitz had a third child, actually their first, and they named him Seymour. And no he didn't die as an infant, as Harriet theorized, since he appears at age 27 in 1930. We'll have to search and see if we can find any other evidence of his life after that. Since the younger children changed their name to Robbins, perhaps Seymour did as well.