I've just realised that you have indicated a year of death for John Keane Lockhart (where does the Keane appear, please) in your first post - 1888.
Three deaths on ScotlandsPeople where the ages are 67, 49, 64 and 0 - so not any of them. But there is one in England in Morpeth RD, but he is aged 53 (allegedly). Still no Keane or initial K in the name and 53 or so is the wrong age for your man. The given birth year is cir 1843 so this one doesn't look likely either. Did he die overseas? Did the family emigrate?
The births/baptisms of John A, Isabella, James, Ellen/Helen and Ann all appear in the Army register of baptisms and births. The father's regiment is shown as the 26th Regiment. Fernancy Jane and Mary Frances do not appear at all in this index.
The 26th Regiment ceased to exist in 1881/2 when it amalgamated with the 90th Regiment (Perthshire Volunteers) to form the Cameronian Scottish Rifles (modern name).
A John Lockhart enlisted in the 26th Regiment in 1860 at the age of 20, so he would have been born cir 1840 and his birthplace was Irvine, Ayr. He left the army in March 1882 following his second period of engagement and his wife was Ellen Moffat. The place of discharge was Hamilton, so it is possible that they continue to live there and that Mary was born later that year.
Nell
Edit- just realised that the 49 year old who died in 1888 could be that John, given the revised date of birth.