Hi Michelle and welcome to Rootschat.
Here is the 1861 census for the Maindonald family.
address 2 Town Hill
John Hooper, head, age 30, (cant read his occupation) born Guernsey Castel
Sophia Hooper, wife, age 32, family dressmaker, born Guernsey St Andrew
John Hooper,son, age 6, scholar born Guernsey St Peter Port
Mary Hooper, daughter, age 5, scholar born Guernsey St Peter Port
Daniel Maindonald, father in law, widower, age 60, shoe maker born Guernsey St Andrew
RG9 4383
ed 3e folio 50 page 23
civil parish of St Peter Port
Here is the census for the Sparkes family in 1861.
Names was spelled Sparks on original image.
address 29 Park Street
Joseph Sparks, head, age 54, gardener born England
Mary Sparks, wife, age 58, grocer, born England
Francis Sparks, son, age 14, brush makers apprentice born Guernsey St Peter Port
Thomas Shute, boarder, age 25, student, born England
RG9 4383
ed 5e folio 76 page 14
civil parish of St Peter Port
No sign of Teresa or Katherine under the name Sparkes.
But found this could this be Teresa Sparkes and Thomas Maindonald? in 1861
Thomas Maindonald, head, age 20, sailor born Guernsey St Peter Port
Teresa Maindonald, wife, age 22, family
serv (very hard to read) born England
RG9 4383
ed 3e folio 50 page 24
civil parish of St Peter Port
I hope this helps.
Nicky