if Matthew was Manx then there are very few Matthew Cowins I can see - one that fits is Mathew s/o Mathew Cowin + Ann Horne (Hoon in one bapt) married Ger 17810501 (both of parish - witnesses charles cooper of peeltown + angus munn revenue officer which could imply Ann was non manx - I can't find any bapt for her) - there would appear to be a will for Mathew snr in 1789 but can't see any further signs of Mathew jnr or Ann Horne