Updated: Jan 30, 2019
Two of their four known children are in this photo. Their son, James H. Leonard, who was their second born child, born in 1890, and Ethel M. Leonard, their third-born child, born 1892. (She later married William Bross). Their 4th child, Albert Jay Leonard, wasn't born until 1895. Therefore, this family portrait appears to have been taken around 1894.
The question is, why wasn't their first-born child, Elma, in the photo? Elma was born in 1887, so she would have only been seven years old at the time. See also, the portrait taken years later of James, Ethel & Elma.
For more information about Lewis Leonard see the Leonard page.