Sorry about giving you the Rushen Elizabeth.
My attention must have wandered when I was reading the IGI.
One question that I have is, as she always appears as Isabella Gilmore(our) in the census and burial info (although she appears as Elizabeth in the marriage and some children's christening records), have you also looked for an Isabella. The IGI has two Isabellas, who were christened in German in the period 1789-1801. One appears unmarried in the 1851 census. One was the daughter of John Shimmin and Isabel Mylecheest, the other the daughter of John Shimmin and Jane Lace.