Hi Sue,
My interest in this line is that my 4xgt grandmother was Catharine Taggart d/o William and Elinor Bridson:
1) There is an IGI entry ex Register for the baptism of Wm Taygart 1699-04-25 Santon, no parents given. - but there is an IGI member submission which claims he died 1700, the s/o Wm & Isable. The baptism of 1700-12-20 Santon is also ex Local Record. However as you point out this latter date is after the death of grandmother Margery als Bridson. BUT - What if BOTH entries are correct? William (3) and Isable Harrison had William (4a) ca April 1699, baptised him on the 25th, and so he was alive & named in his grandmother’s Will. The infant died in early 1700 and the next child of Wm (3) and Isable was also named William (4b), bptd Dec 1700. Thus in 1721 William (2) named his grandson William (4b), but the child was not the same one as named by Margery in 1699. In June 1787 when he died William (4b) was in his 87th year, although probably not yet 87 yrs old.
2) The Marriage of William (3) Taggart and Isable Harrison [or Taggart?] has not been found. Frances mentioned in a recent post that the Santon Registers for 1695-7 are incomplete, so they may be in those. The IGI entries for their children give only “William” or “William & Isable” as parents. The only mention of Isable Harrison was in the dispute arising between the two family factions after the death of William (3). I have had a quick trawl through Harrison Wills/Summaries, but found nothing yet.
3) What happened to Ballakew? Did William (4b) inherit? The births of the children of Wm and Jane Moor were all given as “of Ballakew”, but they were IGI member submissions. The Will of Jane 1732 may well prove informative. They had a son William in 1732, bptd 2 days before Jane's burial. If the same William (4b) then married Elinor Bridson he would probably not have named another son William, at least not while the one b.1832 was still alive. I don't have Malew Burials, but there may be an appropriate death of a child or young William Taggart before 1747, when William (4b) and Elinor named a son William.
As usual more answers, more questions!
Rgds John L