Hi Karl
I have found them in 1851 minus Robert who it seems died in1849. I have searched the same area in 41 and 61 but did not find them, sorry but Chester is to big a search without a name index.
1851 HO107-2172-F 254 Trafford Street St Oswald ChesterSarah Allmark head widow 31 pauper born Mollington Chester
George son 11 scholar Chester
Hannah daug 6
Robert son 4
Catherine daug 1
?? Lloyd female lodger 30
Thomas Lloyd lodger 10
Elizabeth Maddock lodger 38 straw bonnett maker Chester
Can I suggest that you search the
http://www.cheshirebmd.org.uk/ to see if you can pick up Sarah either her death or another marriage maybe ?
hope this helps
peterbennett