Nice to hear from a fellow Ferguson researcher! I have now accepted that my branch of the family is not connected to Annie Laurie. My John came from Balqhidder in Perthshire and not Craigdarroch. That being said he did start a distillary in Perth, Ontario and sold a good scotch whisky which he called, apparently, Craigdarroch.
I do have a book called the Lauries of Maxwelltown which has the family trees for Annie etc.
Anna, as she should be called, married Alexander Fergusson and had, according to the book, 4 children, James, 15th Laird of Craigdarroch, Jean who married Robert Riddell, Robert, who married Clemantina Douglas and, I think one other.
James first married Euphemia Nisbet who died in childbirth with their first son Alexander, the 16th Laird. He married Deborough Cutlar and their son was the grandfather of your Captain Robert Cutlar Fergusson, 19th Laird of Craigdarroch.
There is lots more but I can't see a Matthew just now. Let me have a further look through the book and I'll get back to you.