I might be able to help you along a bit...

I have six siblings for Barbara Ann Catto so far:
William Catto, b. 1884 New Deer; d. 1929 New Deer.
Alexander Catto, b. 1886 New Deer; d. 1960 New Deer.
George Pirie Catto, b. 1888 New Deer; d. 1963 New Deer.
m. Mary Bella Souter, 1915 New Deer. They had five children that I’ve found so far.
John Catto, b. 1890 New Deer. He appears to have emigrated to Australia and married Elizabeth Ann Evans, 1928 Sydney. They had at least one child. I haven’t found a death for John.
Gavin Catto, b. 1893, New Deer; d. 1959 New Deer.
Mary Catto, b. 1895, New Deer - I haven’t managed to find out what happened to her after 1901.
There is also a half-sister - Georgina Simpson or Bruce, also known as Georgina Catto - who was the illegitimate daughter of Mary Bruce, born prior to her marriage to Thomas Catto. She was born in 1880 in New Pitsligo and died in 1957 in Aberdeen.
Ruth