Hello Gadget,
Great to hear from you again. I've been putting together trees about the Chisholms from Gairloch and have done some checking. You are quite right. Isabella married Alex McLennan in 1848, (after John (I'll call him jnr ) Chisholm died, and she died in 1859 age 47 at Melvaig. Her brother Murdo was informant on the death, parents were John McKenzie & Margaret nee McKenzie.
I think ,but haven't been able to prove that John(jnr) Chisholm was the son of John (snr) Chisholm & Margaret McLean (John (snr) later married Ann Fraser in 1828, and they are in the 1841 and 1851 census)
John (snr)died in 1857 at Big Sand. He was the son of William Chisholm from Isle Longa, as shown on his marriage to Margaret in 1804 (She was the daughter of Murdoch McLean, also from Isle Longa)
When John (jnr) married Isabella McKenzie he was from South Erradale and Isabella was from Melvaig. So I linked him with a ? to John and Margaret as other members of this family went to live at Badachro, which is close to Sth Erradale.
Also I know John (jnr) is not the brother of Flora as her brother John married Margaret McKenzie who was a sister of Isabella & Murdo.
As you say Chisholm is not a common name and so we still have the mystery Margaret with Mary & Jess. I might have to use a process of elimination to see who she could be. I wonder if Mary and Jess could also be sister's in law, but I'm leaning more towards your idea that this Mary is James Allan's mother, and it would make sense for Alexander Chisholm & Mary McRae to have a daughter called Mary, making a link to Flora (McGregor, nee Chisholm) & John Chisholm.
I did read somewhere that following Culloden the McKenzie's moved tenants living on their lands south of Inverness (Chisholm territory) out to the Western areas. This may also explain why my McGregors were in the Melvaig and Annat areas.
I'll keep digging. As I say, when you find a brick wall, dig sideways! I hope you can follow my ramblings.
Cheers,
Ann