Re William & Mathias a couple of possible baptisms for you:-
William Rigding 19th May 1793 All Saints & St Margarets Chattisham Father William Mother Mary born 20th March Late Fenning
Mathias REGEN 2nd April 1797 All Saints & St Margarets Chattisham
Father William Mother Mary born 30th March recd 4th June Late Fenning
EDIT other possible baptisms:-
Hannah Ridging 5th September 1790 William/Mary born 19th August late JENNINGS?
Thomas Rigen 30th November 1794 born 24th November recd 10th May 1795 late Fenning
Both same venue.
Possible marriage for parents:-
William Ridging of Freston to Mary Fenning 13th February 1789 Ipswich, St Matthew.
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