Joseph Vernon Grant looks to be about 8 in this photo, but he was always a big husky kid, so guessing photo was taken in approximately 1935. Back of photo says: "Flood waters in July. Our house is built on other side of white shack (very far right). Vernon sat down while wading over to the house to take these pictures with Fred." From the pictures where Margo and Jim are shown with their father Fred. This is identified as Square Deal. Square Deal was a temporary boomtown that sprung up during the building of the Fort Peck Dam in Montana..
The boomtown shack they lived in appears to be about the size of a on room studio apartment in this day in age (2018). There was likely no indoor plumbing.
Because of the coats Ann Grant and her son Jim are wearing, Joyce suspects it is the fall of 1937. Baby Marjolaine/ Margo would then be about 9 months old. Jim would have Jim would have been 3 1/2.