I found a Joseph A. Jangro in the 1900 census who lived next door to John Jangro (m. Nancy Jangro)
At the time of the 1900 census Joseph A was 48 and he is a widower. He lived with children Aleena Jangro (!5), Mary Jangro (13), Iris Jangro (13), and Nellie Jangro (7).
I don't think I know who this Joseph was. They lived next door to John and Nancy Jangro in Florida, MA in 1900 and both worked on the B&M Railroad. Were they brothers? cousins?
Joseph A. was born in Canada and may have moved down to US not too long prior. The oldest daughter Aleena was born in Vermont in 1884.
There's a Joseph P Jangro from the same western Mass. area born in 1880.