I have a copy of the actual census so don't need that, but thanks for the offer. I also had the record for the marriage of William Dent to Jane Hill where William is listed as Widower. I haven't been able to confirm who his first wife was or if there were any children from the marriage though I have my suspicions.
Richard Dent married in WI is interesting. The Richard Dent I believed married ca. 1853 Canada as his wife and the first 4 of his 7 children were born there. He did however have two children born in WI. I suppose it's possible he could have married in WI and moved back to Canada but I wouldn't think so.
According to the UK records online I can attribute John, David1, Richard, Joseph, Susannah and Charlotte to William Dent and Jane Hill. There is a nine year gap that David2 and Charles fit into perfectly.
We know that David and Charles were brothers according to the 1851 census where David was head of household and Charles relationship is listed as brother. We also know because of the 1871 census you sited that Charles had a mother named Jane and her age fits with Jane Hill married to William Dent. We also know that both David and Charles were born in Nettleton, Lincolnshire, Eng where 5 of the Dent children were born.
William Dent died 30 Sept 1852 in Nettleton.
I feel pretty confident putting both David2 Dent and Charles Dent in the family of William Dent and Jane Hill. Was just hoping for confirmation.