I have what could be a clue linking the two Elhilow families in the US.I was reading over my genealogical information.My Aunt Mary Kirdahi (Elhilow) stated the following:
"Sometime in 1929 Beshara was having a conversation with a relative of his who had come to America some time prior to Beshara. Nahoom and his brothers were given the family name of Elhilow by immigration officials at Ellis Island when entering the country. At that time Beshara agreed to have the family name legally changed from Hilow to Elhilow in order to maintain a uniform family name in America."
It looks likely that the Nahum Elhilow you know of could be the Nahum Elhilow who spoke with my great-grandfather, Beshara Elhilow, which caused him to change his name to Elhilow.Especially because she states, "Nahum and his brothers", and I have not come across any other Elhilow's in the US besides the ones you know you are related to and the ones I know I'm related to.
We don't have a direct link, but we have evidence that the two families knew they were relatives.Beshara would have been a generation younger than Nahum, I think.Beshara was probably born around 1880 - 1890.However, his father's name was Boulous Al Helou and remained in Jezzine, Lebanon.Boulous could have been one of the other brothers of Mansour who remained in Lebanon that you're looking for.God, wouldn't that make life exciting for us genealogists?