I can only find one family that fits the names you’ve given:
The only marriage on Freebmd at
http://freebmd.org.uk/cgi/search.pl between a Sarah or Sally Youles and a Savage is in Colchester in the Dec quarter 1896 where the bridegroom is George Savage. If you order the marriage certificate, if you don’t already have it, you’ll get fathers’ names.
In 1901 living at 150 Butt Rd, Colchester were
George Savage head marr 28 Grocers assistant b Newington London
Sarah Savage wife 26 b Benwick Cambs
George Savage son 3 b Essex
Arthur R Savage son 1 b Essex
1891 - can't find her
1881
On the Common, Benwick, Cambs
Robert Youles head marr 44 engine driver b Benwick
Mary Youles wife 42 b Benwick
Sarah J Youles dau 12 scholar b Benwick
Mary L Youles dau 10 scholar b Benwick
Salley Youles dau 7 scholar b Benwick
Florence Youles dau 5 scholar b Benwick
Robert T Youles son 2 b Benwick
1871
Piccadilly, Benwick
Robert Youles head marr 34 engine driver b Benwick
Mary Youles wife 32 b Benwick
Martha Youles dau 12 b Benwick
Susan A Youles dau 5 b Benwick
Sarah J Youles dau 2 b Benwick
Mary E Youles dau 3mths b Benwick
So it seems as though Robert and Mary had two daughters, one named Sarah, and another named Sally, as well as Susan who emigrated. Using Freebmd again there’s a Sally born June quarter 1873 in North Witchford registration district which includes Benwick
David