Hi Shanreagh,
I have PM'd you, per request. I look forward to hearing from you.
In response to your questions:
1) GV Revision Books:
I have not looked at Tamlaght, but have for Drumacarney and now Ballyness, Dungiven (as a possible origin of Leslie Irwine / Irwin, who emigrated with two of William Kerr and Betty Irvine's sons and settled in Philadelphia). There is a separate thread about what I have been finding about him.
You are correct that it is a rich resource.
2) The Miller family:
I have not looked for them seriously yet. My previous attempts were defeated by the commonness of the surname in the area and my unfamilarity with or lack of access to records. I put this whole question of the origin of William Kerr and Betty Irvine aside for decades and only have returned to it since mid-February. Only recently have I realized I should be looking at spelling variants such as Carr and Irwin, so in a way I am starting over.
I believe that Billy Miller lived about 4 miles from N. Limavady towards Londonderry. His unnamed sister who married an unnamed Kerr from Scotland had two children, William (m. Betty Irvine about 1831) and John (m. Eliza Torrens about 1841). Betty died about 1844, and I infer that her children then lived with, or had very frequent contact with, their mother's relatives, since I have the most detailed information about them. That the names of Billy Miller and two of his four children (William and Peggy who married Robert Gant / Gault) suggests that they also were alive in the late 1830's and 1840's. I think these names came from the memory of William and Betty Kerr's daughter Eliza, who emigrated with her uncle John and his young family in 1848, when she was 14.
I also suspect that Billy Miller's father was William, based on his nickname Billy and son William. His sister died when her Kerr sons were very young, so perhaps 1815?
As far as who were "Limavady people," I have three brothers Kerr who came to Newtown Limavady, "bo't a township," and set up linen and corn mills there. I have not yet found any evidence of this. I also know that the fourth child of William and Betty Kerr, Alexander, was born "in Newtown Limavady" in 1840-1842. His older sister Eliza wrote in her bible that she was born "in County Limavady" and told her daughter that she was born near Londonderry.
Thanks for any insights you can offer. I'm finding a steep learning curve with finding and interpreting records, let alone interpreting the notes that I inherited!n