Hi,
There is no baptism for Mary Ann KING at St Mary Magdalene, Twyning circa 1825.
However I can confirm that both Robert KING (GRO:1842 Cheltenham 11 221 Mar Qtr) and Kate Potter KING (GRO:1854 Cheltenham 6a 392 Mar Qtr) do not have a father on their respective birth entries. I do not have the data for post-1837 baptisms in Bristol for Henry KING.
I also found the following 2 marriages at Twyning which may be relevant:-
John KING married Elizabeth GARNER at St Mary Magdalene, Twyning on 18th October 1803, by Banns.
John KING, Widower, married Ann RUSSELL at St Mary Magdalene, Twyning, 18th November 1811, by Banns.
Victor