My, time moves as slowly as the dead, doesn't it. this post was over 18 months ago and here is an offer of an answer and I am so neglectful that I forgot all about it.
To answer you, Christopher, the family were from the established church. In this case the records were in a COI church, if I recall.
Someone on another list kindly found the parish entry for Samuel's birth in 1863. Killynumber, Kilcronaghan Parish. Of course that led to further entries and his parents were apparently from Murmeal and Killynumber, respectively. There are some records that go back to about 1802 in Tullylrowan and Matilda Campbell was possibly from Bellygaly, b. abt 1825.
Rebecca Verner Magill/McGill's parents were listed incorrectly by my original informant. Her father was William Magill from Newton Limvady and he married Betsy Verner. It is my understanding through other distant family connections that the Verner name is still alive in the family line.
Another quirk- maybe not so quirky in that day and age, is the fact that it appears that Rebecca's sister married her husband's brother. Through that marriage a Stewart gets added to the mix by a descendant.
So, as you can see, with one wee crack in the wall I found another abundance of relatives and slid back about sixty years thanks to the kindness of someone else, for which I am eternally grateful.
Thank you for taking the time Christopher to bring this post to the fore again. Who knows maybe someone out there will find another tidbit for me, or even better, will not give up hope!