I assume that you have already found this site:http://www.rootsweb.ancestry.com/~nyggbs/Transcriptions.htm
The information I can offer was taken from there, particularly this link;http://www.vc.id.au/tb/index.html
Tikwis Begbie (“British Guiana Colonists” – wonderful summaries) has John Williams [sic] Ralphs marrying Katherine Sarah Wilhelmina Hancock on 29th June, 1877. She appears to have two sisters: Alice Helen Elvira Hancock, who marries David Milne Smith on June 6th, 1882, and Jessie Hancock (b. 1/12/1887; d. BEF 1928. She marries Edward Augustus Hubbard on April 18th, 1876. My interest and connection is with her: She and Edward have three children: Jessie Alphina [Tikwis has the spelling ‘Alfina’] Hubbard; Alice Maud Hubbard; and Thomas Hancock Hubbard. He is my great-grandfather.
The three Hancock sisters’parents are Thomas Hancock (d. BEF 1876), and Helen [can’t find her maiden surname], born ABT 1811, died 4/4/1867. No date for marriage.
Tikwis has the following five entries under Ralphs [site had minor updates in July]:
RALPHS, -, wife of W.J.
Married RALPHS, W.J.
RALPHS, Harriet Norine
Born: 4 NOV 1880, British Guiana
RALPHS, John Williams
Married HANCOCK, Katherine Sarah Wilhelmina: 29 JUN 1877, St. Philip's Church
Born: 27 MAY 1879
Married RALPHS, -, wife of W.J.