Hello
Following on from Hazelnut, looking at the 1851 census for Sarah Jnr who declares she was born in Pontefract, the baptism entry you need to look at is the 13/03/1833 Pontefract. It is likely that the 'Vicar' may have recorded whether or not Sarah senior was single / married etc. On the 1851 census she indicates that she is a widow
A search of the records may reveal 'other siblings'
Try this link
http://www.genuki.org.uk/big/eng/YKS/WRY/Pontefract/
There is also a bp for Sarah THORPE 3/10/1790 Emley d/o William & Grace THORPE if this is the coreect family there are 13 bp entries for this couple in Emley Yorkshire ( in reality only poss 5 as there is duplication of entries) also a LDS member entry
www.familysearch.org
As regards the 'father' this may have been made to make Sarah jnr look 'respectable'!
Elsabels