Can you post a link to the 1851 census you have found for the family ?
There is a Ferris family in the Cricklade & Wooton Bassett Workouse in 1851 -
Mary Ann Ferris age 33 Born Lydiard Tregooze, Wiltshire
Charles Ferris age 12 born (as above)
Phoeby Ferris age 9 born (as above)
Henry Ferris age 6 born (as above)
Rosanna Ferrris age 3 born Lydiard Millicent
All described as paupers.
The ages of Charles & Phoeby fit very well with the names you gave, but obviously other names don't fit- what sources do you have for the family information ?