I thought I really should check my own Family Tree for Burdock's and found I already had an Anne Burdock 1804 married to Edmund Marfell 1800 and it turns out she was a sibling of Lydia Burdock who married John Bennett and Thomas Burdock who married Mary Bennett.
Edmund Marfell & Anne nee Burdock had 6 children including Abia 1835 and it is she that was on the 1851 Census with John Bennett and Lydia nee Burdock - Apologies to Trudy; I answered your question about Abia Marfell without applying enough thought. The Abia I mentioned in my reply to you was born 1783 :

Year: 1804
Month: Oct
Day: 14
Parents_Surname: BURDOCK
Child_Forenames: Anne
Fathers_Forenames: Tho[ma]s
Mothers_Forenames: Anne
Mothers_Surname:
Residence:
Occupation:
Officiating_Minister: Thomas Davies
Event: Baptism
Memoranda: daughter of
Notes:
Register_Reference: P346 IN 1/2
Page_Number:
Parish_Chapel: Upleadon
Soundex: B632

Checking LDS they have a marriage between Thomas Burdock and Anne Church at Rendcombe 16 Jun 1793.

According to the F o D site Parish Records, their first child Anne was baptised 29 Jul 1796 and buried 21 Aug 1796. Second child Mirrium baptised and buried 1798, then along came Lydia 1799, Thomas 1803 & Anne 1804 already documented, followed by John baptised 4 Jan 1807.

Jim Ashton