Just so.
I think that the parents of Margaret/Maggie Myron or McMeeking were Charles Lennox Myron 1839-1917 and Mary Sellar; and that she was born in Botriphnie on 5 September 1858 and registered as Margaret Sellar. (As she was illegitimate she could only have been registered as Myron if her father had accompanied her mother to the registrar's when she went to register the birth, and signed the register at the same time.)
At FreeCEN
https://freecen1.freecen.org.uk/cgi/search.pl there is a family at Tennanton, Botriphnie in the 1851 census consisting of James Sellar, widower, 53, blacksmith, with six children including Mary Ann, aged 12, and his 80-year-old mother. Have a look at the original document at
www.scotlandspeople.gov.uk (SP).
I think these could be - probably are - Margaret/Maggie Myron or McMeeking's mother and grandparents. Look at her birth certificate on SP. Was Margaret/Maggie born at Tennanton? If so, then it's quite understandable why she was taken in by her father's parents, because her mother's mother was dead.
I think you will find that Mary Ann was the daughter of James Sellar and Barbara Garden, baptised 29 December 1838 in Botriphnie. She married Alexander Bowie in Botriphnie in 1863 and died in Grange in 1879 aged 40. Check her marriage certificate on SP to see if she was living at Tenanton at the time of her marriage.
James Sellar, mmn McPherson, died in Botriphnie in 1889 aged 87 (if you believe the deaths index at SP) or on 26 May 1889 aged 88 (if you believe the death notice in the 'Elgin Courant'). Check his death certificate on SP to see if he was the widower of Barbara Garden.