Something else to mention with regard to Scottish research. Whilst not always rigidly adhered to there was a Scottish Naming Tradition:
MALES
Eldest son - named after his paternal grandfather
Second son - after his maternal grandfather
Third son - after his father
Fourth son - after his father's eldest brother
FEMALES
Eldest daughter - after her maternal grandmother
Second daughter - after her paternal grandmother
Third daughter - after her mother
Fourth daughter - after her mother's eldest sister
So, as per the tradition, Margaret Handlin/g Milroy, was indeed named after her maternal grandmother Margaret Morrow Handling. (My own mother Margaret Ingram Spence was named after her maternal grandmother Margaret Ingram and she had 3 cousins who also had the names Margaret Ingram as Christian names.)
Annette