Marge was Dorothy's aunt--her mother Pauline's younger sister. She was born in 1924, making her 20 years old at the start of 1945.
In 1945, Marge and her son, Lee, were living with Dot and the family while her husband served in the military. She worked downtown at the Morrison Hotel with her friend and Dot's neighbor, Betty. (Betty was short and Marge tall. The were nicknamed "Mutt-and-Jeff" by Dot's mom, Pauline.)
Marge would also have a daughter, Joyce. They eventually moved to Mattoon, Illinois, and then Michigan City, Indiana.