Thank you all very much for your helpful replies, and I apologize for my delay in reacting. I am very sorry if I didn't explain this adequately, but I was only really looking to discover any children who are additional to the one I already knew of and had listed -- not to know what happened to the listed ones once the family reached Canada. I already knew that. But thank you anyway.
That said, Sandra, I hadn't found Alexander MacDonald in the '51, so I am grateful for that tip.
Lisa, I too was struck by the odd gaps in 'children production' in this family. But I haven't been able to fill them.
Assuming there is anything to fill them with. But I will certainly check out the 1824 male birth you found (on Scotlandspeople) -- same parents and parish as other births, so this looks very promising; thank you! One of the children -- the eldest, Thomas -- certainly stayed in UK but moved away from Inverness. (No work there). And thank you for all the Canadian research tips -- certainly a couple of them were fresh ideas to me and I am sure will prove helpful. Several of Sarah Davies' siblings (and, indeed, nephews and nieces) also moved to Canada with their spouses; but no known-of interactions with the MacDonalds post move, unfortunately. (I have not yet been able to identify William MacDonald's parents and siblings to see if any of them might have crossed the Big Pond; but I shall work on that!)
Brigidmac, it had crossed my mind too, a while back, about a possible earlier marriage for William and some of Jane Logie's siblings being half siblings; but now you've reminded me of that possibility again I shall certainly investigate it -- thank you. If birth date I have for William is correct, then he would have been about 24 when he married Sara, so an earlier marriage (and offspring) is not inconceivable.
Cosmac, thank you for the website reference. It looks interesting and helpful.
Once again, sincere thanks to all for all your help.
CELTICANNIE