Great to hear from you! I sent you an e-mail, but perhaps you did not get it, so I'm putting a reply here on the board. I've only been doing my research for about 5 months, but I am happy to share my findings with you. I am descended from John's brother Richard, the youngest of the Montgomery's, through his daughther Nancy, who married a Quantz in Innisfil. Two of her sisters married Warnica's in Innisfil and at 15 Nancy came to live with one of them. I have her obituary and there are some photos of her on the Innisfil Historical Society's website (you have to do a search for the name "Quantz" to find her). She was called "Black Nancy" because of her very dark hair.
I'm particularly fascinated by your John and have been doing a lot of research on the Rebellion and his "role". Also, my family is originally from Barrie and John died there!
I look forward to corresponding with you and am hoping you have some family stories you could share (about any of the Montgomery's). I'd also be interested in scans/copies of any pics/portraits and documents/papers. Have you been doing your genealogy for long? I am in Mississauga. Please feel free to e-mail me directly at: firstname.lastname@example.org
I look forward to hearing from you again.
P.S. Have you seen the small watercolour of John Montgomery that the Toronto Reference Library has? I saw it a few weeks ago and took a digital photo of it - they are reproducing it for me. Apparently there is another portrait of him at Mackenzie House on Bond Street (haven't got in there to see it yet).