Park and Hinderson/Henderson Family in 1851 Hamilton, ON Census

I have several questions concerning the brick wall I have hit.  In the 1851 Census for Hamilton, ON my great great grandfather, William Park is listed with his wife Mary and three boys, William, John, and Robert. there are also 5 Hinderson/Henderson young people living with them and they are all listed as Family.

I have never been able to trace bach any further for William Park or his wife Mary (Paton) Park. Both were supposed to have come from Scotland.  William possibly by himself, and Mary with her family, but that is just flimsey oral history.  They met and married in 1844 in Gore District, Barton Township, Wentworth Co., Canada West (Ontario).

I have not been able to find any other census records for William and Mary.  I know 2nd son John married and moved to Detroit, MI and that line of the family is now scattered around MI.  There is no other trace of 1st son William, and 3rd son Robert I have quite a bit on (that is my direct line).

Also I have not been able to find any other trace of the Hinderson/Henderson children after the 1851 Census.  there were three boys (James 24, Mathew 20, Andrew 17) and 2 girls (Elizabeth 20 and Alexandra 14).

If anyone could provide suggestions or possible connections on how I might continue my search it would be greatly appreciated.

Robert Park