Back right: Isobelle Johnstone.
The rest I am guessing.
Back left: probably Eleanor (Mrs Barkley).
Why? Because Isobelle says she
gets on well with Eleanor and that the other two sisters get on well together.
Front: Margaret Stockman Johnstone (Mrs
Fiskin) and Elizabeth Jane Johnstone (Mrs Porter)
But which one is which?
Below, I tried to get a clearer picture of Eleanor (if it is Eleanor).