Well, I finally found sparse obits for the two sisters and both their deaths are sad.
The first sister - Eldora/Eudora was born about 1888 in PA. I found a blurb that said she died at 3 years old of scarlet fever in PA (obit attached). I never thought to look for her as Dora!! Just happened upon her obit while trying a search for Colborn/Colburn.
The other sister Eleanor/Elnora died young as well. She was born in 1896 in PA and moved with her family to Newark, NJ. At some point between 1915 and 1920 she married a man named Ralph Beebe. In March 1920, she died at the age of 23 in California, although she was living in Newark at the time. No idea what she died of yet or why she was in California.
Their brother, my great-grandfather, Melvin Russell Colborn also died young. Had lung issues as early as 1899 when he was about 18. He died at age 34 of pulmonary tuberculosis. I think it may have been caused by his early career as a house painter.
The only sibling to live long was the oldest child, Jessie Leah Colborn (who married 3x), who died at age 72 in 1953.
So I finally found the two sisters, Eleanor and Eldora/Eudora but of course I am now trying to find out more. I am VERY lucky to have a picture of Eudora/Eldora, as well as my great-grandfather and his sister, Jessie.
So there were four children in all:
1. Jessie Leah Colborn (she married 3x)
2. Melvin Russell Colborn (who went by various names just to plague me) - he died young as well. Had lung issues as early as 1899 when he was about 18. He died at age 34 of pulmonary tuberculosis. I think it may have been caused by his early career as a house painter.
3. Eudora/Eldora born 1888, died 1891 of scarlet fever
4. Eleanor Gertrude Colborn Beebe - born 1896 and died 1920 at age 23 (cause unknown)