Hello
"Minnie (f.): originally a Sc pet-form of Mary. It became common in England in England in the 19th C and was often used as an independent name. Not in CMY." - Oxford University / Clarendon Press 1945
Sc - Scottish
Not in Charlotte Mary Yonge (Two volumes 1863. Revised Ed. 1884)
Officially Mary, but has been used it seems as a pet name for others.
Obviously a name in itself - Minnie.
Officially the pet name for Wilhelmina was Mina.
Minnie was also an affectionate name for Mother, [asking for something as a child - go and see Minnie, meaning go and see your Mother], or it can be used as 'mother's darling' an affectionate pet name given to a child by the mother. Mother use - mynnye.
Minnie has been used as a pet name for others too and only family knowledge, or finding the ancestor in other records may confirm the real name, or spelling, if the name was not Minnie at Birth or used simply as a pet name.
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Scotland - also minny, minni, mihnny Shetland News - 12 February 1898; also variations mynnie, mynnye, possibly minnye.
If she was called 'Minnie' (pronounced) and she was Scottish, search Scotlands People by surname only.
If buried and in Scotland, any Headstone Memorial, or official M.I.?
Mark