I have not heard the story of the duel and the baby before, and you do not say when this might have taken place.
The last fatal duel in England took place some seven years later, on 19 October 1852, The last Scottish duel on Scottish soil took place in a field at Cardenbarns to the south of Cardenden on 2 August 1826.
The more information you can give about the people you mention, the more chance there is of someone else connecting with your family.
Dates and places of births, deaths and marriages all help to place families.
Professions also help.
'My great-grandmother mother was a Douglas from Montrose' does not give many clues to follow up! But a bit of flesh on the bones makes further research possible. But if we are told who she married, what his profession was and where the children were baptised, then we can get to work.
Maybe it is time to update the information in your profile?