Just something that did catch my eye when looking at some of your Lockwood's known children- the midname of "Fletcher" jumps out( again likely an ancestral surname" -most specifically Andrew whose middle name on his marriage record in the US is ided as Fletcher. Oddly enough Joseph Pringle who married Deborah Dafoe had a brother Simeon who married Nancy Dafoe and in turn 2 of their grandsons received the midname of Fletcher as well- Daruis Fletcher Pringle and John Fletcher Pringle. I have not come across this name in any of the Dafoe lineage.
I don't know if this is possibly a clue???