They appear to be two brothers and one more distant cousin. (More details below)
I suppose these are the ones you're look for:
William and James Pond were sons of Daniel Pond and Mary Pinfold. Joshua was the son of Joshua Pond and Ann Theed. There was also a Daniel Pond in Cornwall, in one census it says he was born in Bucks, in another it says Gloucestershire.
There are a lot of Ponds in Burnham in Familysearch. I'll leave it to you to sort them.
Joshua Pond, born about 1795 in Burnham
(in Familysearch: born 16 October 1796 in Burnham, son of Joshua Pond and Ann)
(IGI batch M130211. Joshua Pond and Ann Theed married 8 Apr 1782 in Burnham)
Home in 1861: Bodmin
Gardener
Wife: Mary, born 1798 in Essex
William Pond, born about 1799 in Burnham
(In familysearch: born 10 Feb 1799 in Burnham, son of Daniel Pond and Mary)
(IGI batch M130211. Daniel Pond and Mary Pinfold married 17 Feb 1798 in Burnham)
Home in 1841 & 1851; Boconnoc, Cornw.
Wood bailiff
Wife: Mary, born 1799 in Boconnoc
Children: Edwin, Leonora, Thirza, Jemima, all born in Cornwall
James Pond, born about 1801 in Burnham
(In family search: born 15 March 1801 in Burnham, son of Daniel Pond and Mary)
Home in 1841, 1851 and 1861: Polperro, Cornw
Schoolmaster
Wife: Elizabeth, born 1805 in Breage, Cornw
Children: Eliza, John, Ann, Emily, Elizabeth, Jane, Easter, Margret, James
Daniel Pond, born about 1804 in Bucks (or Gloucs in 1851 census)
Home in 1841, Boconnoc, in 1861, St Austell, Cornw
Carpenter in 1851, Painter & glazier in 1861
Wife: Ann, born 1810 in Cornwall
Children in 1841: Caroline, Daniel, Emma