Hi Valda, well, grandma had just one sister (and a brother in the navy who does not seem to have married). The sister was Emma Mallin (no second 1st name) who we have from birth in 1876 at West Bromwich to the 1901 census, when she is in service at Handsworth, Staffs aged 25. She is not in the 1911 census and we can trace no marriage or death at any time. She has an aunt of the same name and birth date, which can be confusing, but we have the aunt's history right through.
Of course, Victorian families were very large and Bob's mother could be a cousin or such, and we have no reliable info as to why Bob took a stage name or who he got it from. regards dee.