I wondered if there was only one Esther and that there was some other connection between Marjery and Esther. I could not fine one but can add this if you do not already have it.
An Esther Corkish is in Brian's burials 19 September 1835 Rushen aged 49. This corresponds with the August 6 1786 christening of Esther Shimmin to John Shimmin and Catherine Gell, and would make her age at least 20 at the time of her marriage to Christopher Corkish in 1805.
There is also a christening on the same day of a John Shimmin, father John, mother Mary Rawnan.
It looks an though Margery was Margery Hutchin married to John Rone or Roan and that Mary was christened in Rushen on November 28, 1756.
Brian has a March 27 1786 burial for a Catherine Shimmin in Rushen. Possibly Esther's christening was delayed by her mother's death.
Also the Esther born to Mary is an LDS member submission with only an approximate date. This suggests a different source than the Rushen parish records, possibly based on information in a will.
Possibly there were two Esthers, but the IGI only has only one likely marriage (Shimmin) and Brian has only one likely burial (above).
To further confuse things, there is a Nov 11 1783 Rushen marriage of a John Shimmin to a Mary Barran ("B" fo "R", "rr" for "n"?).