As always, Chatters, you have excelled yourselves. It's taken me a while to sort through all the tips and advice and this is what I have found.
Forfarian: There seems to be a ton of reading in your 3 links to records of Kirk sessions etc. Thank goodness we are in 'lockdown' AND it's raining, it will give me time. Meanwhile...
hmcc: Firstly, don't know why I didn't find Mary Gibson Boyes' birth! However, all that is available seems to be the PR of baptism on 4 May 1850 (b. 30 Mar, 1849) where she is recorded as the "N.D. of Alexander Boyes and Agnes Paterson". Other births seems to be "L.D." or "L.S."...I am presuming this means 'natural' rather than 'legitimate'. I tried researching Alex'r but the only one I can find is 6 years younger than Agnes and marries an Agnes McGeorge. But thanks, hmcc, for that snippet. There is no further information on this young lady, not even in other family trees. There is no record of any marriage in the OPRs of Agnes and Alexander.
Now for William. MonicaL... Yes, I can see the birth of William Paterson to Agnes in 1860 in FamilySearch but there is no corresponding information in SP and I am confused as to why, from 9 months later he is known as William McConvle (sic), Wm Conviel, and Thomas W G Conville in the subsequent censuses. In any case, there are no birth records for the various names of this young man, nor can I find marriage or death.
Marion and John Johnston. Yes, hmcc and MonicaL again (gosh, you do work hard for other people, thanks so much!). I have found the 1861 census with both of them who are noted as the son and daughter of James (tailor) and Mary, and the one with John with his grandparents. The names are wrong entirely, there are no Johnstons in this family line so unlikely to be related to Agnes.
The more I dig and pick at this problem, the more perplexing it becomes. How can these people disappear so completely? And appear with no apparent or only very sparse records of birth etc. Even Agnes has no death record (so far). I will see what I can get from the KS records, but it seems to me that either Agnes was VERY mixed up herself, or she had been a bit of a 'goer'!!
Watch this space.
In the meantime, my gratitude to you all for you hard work. Please stay safe.
lydiaann