My ancestor Isobel Harcus b.1759 Papa Westray was most probably the daughter of Magnus Harcus and Mary Shearer. Isobel Harcus married Thomas Leask of Papa Westray and had children born on Papa Westry 1785 - 1807.
Magnus ans Mary had a daughter Jean. I assume this was Jean Harcus who married Robert Scollay. Robert and Jean's son Captain Edward Schollay, born Papa Westray, died 1873 at Nethertown in the parish of Holm, aged 83. Edward's wife was Anabella Margaret Swan d 1889 aged 88, daughter of William Swan and Jean Kedy.
I noticed the Annabella Swan Harcus in your tree and wonder if there is any connection?
Also, a William Harcus was a witness at the marriage of my ancestor Anne Leask to Francis Barnett in Kirkwall in 1819.