The error here seems to be the name 'Harding' on the 1844 marriage certificate and should indeed be 'Hardy' (perhaps the vicar was having an off-day).
Have just checked birth entries of some of their children on GRO's own index and mothers maiden name shown as 'Hardy', not Harding.
That being so, Esther/Hester's parents were James Hardy and wife Sophia Ash (married 31/1/1811 Wareham):
James bp.1811 (obviously the date must be unreadable but appears between entries for 16th June and 13th July) - bur.28/3/1823
Ann bp.25/10/1812
Jane bp.5/6/1814, bur.3/4/1823
Eliza bp.15/9/1816
Hester bp.22/11/1818
Henry bp.3/4/1821
Hannah bp.25/12/1822
(James and Jane above died 6 days apart in 1823 and no more baptisms until 1829)
James bp.27/12/1829
Jane bp.18/9/1831
Maria bp.16/2/1834
So, Esther was actually a Hardy after all, not Harding, as her childrens births testify.
Annette