Thomas McElrath and Grace Engels or Emma Plough

Hi, I'm looking for information on Thomas George McElrath of Newburgh, NY, who possibly had two wives Grace Engels and Emma Plough. They had a child named George Aldridge McElrath born 24 December 1914 in New York.

I have Emma Plough's birth certificate from Kingston, NY. I'm not sure if she is George's birth mother or not. George has Emma listed as his mother on his birth certificate but on his Social Security application he listed Grace Engels as his mother.
Thank you,
Judy