Hello Heather,
I'm sorry to take so long to reply and to thank you for your info. We were away, and then my dad passed away and I'm just getting back to my Scottish research again.
My ancestor was Margaret McGregor, born in Lochcarron about 1783, father Duncan, mother Ann, surname unknown, according to her death certificate. She has a brother John born about 1800 in Lochcarron, but his parents were Duncan and Isabella (nee McRae), so maybe Duncan married twice or Ann is a mistake by the informant.
I can't get a definite link with your Capt John yet, but it was interesting that your family lived near Inverness, as Margaret and her family came to live near Newton, south of Inverness, about 1811, and that's where she died in 1858 age 75.
I'll keep searching and let you know of any breakthrough I make.
Ann