So far I don't have anyone in my tree that corresponds with your relatives but as I hae not gone done the siblings line from the 1841 family which included an Alexander and Robert, we could still have relatives in common (so called). Have you looked in scotlandspeople.gov.uk for your relatives - you buy credits and pay 1 credit to look at a list of people and 5 credits for a certificate. If you know from a death certificate where the family lives it helps rule a lot out and then doesn't cost as much.
Just read your post on the Hunter family.. Many of the Hunters came over to N ireland to live during the plantation period. Many of them settled in the Greyabbey and Ballywalter villages in Co Down. I am a Hunter. You mention an Alexander and a Robert.. Well I have found an Alexander born 1857whose brother was Robert born 1855 and lived over here.. I have another Alexander Hunter who married Isabella Irvine in Ballywalter in 1845.
I am trying to find out where they all connect . If you get in touch I will try and help you
thanks i just found that site, still going thru the lists tho. hopefully i'l turn up smthing. I'm having a hard timefinding family i know every detail of. the furtherst I've been able to go back is my grandmas grandfather James carmichael hunter and have the list of his children