Trents from England to South Africa

My family of Trent's came out to South AFrica circa 1848.

They were John Trent and Ann Lawrence Trent born Cooper, they married in 1835 in St George the Martyr, Southwalk, Surrey in 1835.
I have pretty much covered finding who their children were that were born in England and those born in South Africa.
I am still trying to tie up the children from those children. To many same names, and not to perfect death notice entries. Sure makes researching complicated.
I am going to try concentrate on finding the parents for John then tackle Ann's, her one seems complicated.
So far all I know that on the 1841 census for Newington, Surrey, it stated that John was not born in the county of Surry.

Just below him is a Samuel Long (could possibly be John) Trent age 63 and a Mary Trent age 33, both also not born in Surrey. This leads me to think that "maybe" this is John's father and possibly his sister, as his son John born in 1836 is marked down under their names. Age 6. I have searched for all Samuel's born circa 1778 but am having no joy finding a marriage record or birth record for him or for John Trent who moved to Surrey.
Hopefully with the help of this site someone is connected and I will be able to fit together the missing pieces of the big family tree puzzle.