Have far back have you and Olive's granddaughter traced your family lines in Scotland? She suggests a birth year of c. 1902 for Olive's mother. Is there anything in any document that makes her think this?
There is a possible Tippin/g family whose initial origins point to England and then Scotland (Invernesshire and Glasgow areas). This family includes:
Parents: Thomas Edward Tippin and Mary Garrity
Children: Sarah, Ellen, Mary Elizabeth, Thomas and Jean (there may be more?).
Is there any MacDonald connection for you in your ancestry from Invernesshire? I ask because from this family, Sarah, the eldest, married a James MacDonald and lived at Glen House No.1, as showing on the 1921 census. There is a 'visitor', Ellen Tipping living with them at the time whose age would fit for Sarah's sister.
Monica