UPDATE!
I received a response from the person whose website I was referred to, who said he would pass on my email address to HATTIE'S GRANDDAUGHTER, Doroethy. I received this message from her today:
"Hi, My name is Doroethy, and Hattie was my mom's mom. She was an important part of my life, and I would love to have this picture. I am not sure how it got to [the antique shop]. I have grown children living there, but they wouldn't throw away the picture, or even have one. My mom and Hattie lived on the east side of [town].... I think this is amazing. I am grateful to you for following through on this! Please let me know the best way to retrieve the picture. I am happy to come by.
Sincerely,Doroethy"
I have offered to return the picture to her on Sunday, bringing my mom along too. I'll let you know what happens next.
Isn't this cool? And it took less than a week to find Hattie's closest living relative!!
Delphia