I see seven children rather that six.

How sure are you of date of photo? Looking at clothing of children I think it could have been taken into the early 1900s, though James doesn’t look too old, possibly 70 ish? By your estimate he would be 77 if this photo was taken in 1895. Is the photo dated?
Unless you can match any of the children with other photos in which they have been identified, I don’t know that you will ever be able to find out who they were.
Do you have names and dates of birth for all of James’s grandchildren?
I’m sure one of the dating experts will be able to give you a date estimate for the photo, then by looking at the approximate ages of the children in the photo you may be able to get a rough idea who they are.
The two girls at the front look similar in age (6 or 7?) and they look quite alike - are there any twins in any of the families?