Hi, I found your post the other day when I was researching my Foulis side of the family. Stewart Foulis is my Great x4 Grandmother. I also am descended from her daughter Margaret Dent nee Burgar.
Stewart Burgar nee Foulis was born to Olipher Foulis and Ann Reid in 1807. Stewart is an unusual name for a girl, but we found out that Stewart was a twin. Her brother was called Stewart but he died after being born. We think the parents maybe conferred his name onto their daughter.
We aren’t sure why the name Stewart was passed on for generations, but our Nana (Stewart Burgar’s Great x2 Grandaughter) told us that her mother, Margaret’s Great Granddaughter, told her that their family was descended from Sir Patrick Stewart of Orkney. (Not a nice connection, I know

Apparently, that’s why back through the family, the name Stewart is used quite often. As for William Rendall Burgar, that might be because (now this is Very far back!) Stewart’s father’s Great Grandfather married an Ursula Rendall.
My Mother and Sister did a lot of the research a few years back; since I have taken it up, I’ve researched Olipher’s paternal side to around 1690 and his maternal side to around 1756. On Ann’s side, I’ve researched her maternal side to around 1720 and her paternal side to around 1680.
George Burgar was born around the same time in Westray/Papa Westray (1807). (Westray and Papa Westray were so close that they were both put on the records.) His parents were Andrew Burgar b, 1773 and Margaret Miller b. around 1776. George had six siblings: (ones I can find anyhow), Benjamin b. 1800, Elizabeth b. 1802, William b. 1805, Henry b. 1810, James b. 1815, and Mary b. 1819. George’s paternal grandparents were, William Burgar b. 1754 and Jacobina Setter b. 1756. William’s parents were David Burgar and Marion Harcus. Jacobina’s parents were Wiliam Setter and Barbara Hughson. They all lived in the Orkney Isles.
If you would like any more info, just reply!
God Bless.