G'day James
I have info a bit different to you tho the folks seem the same. My main source is a cousin who obtained info from IoM sources many years ago.
Thomas Cowin (b 22/12/1782 Lonan, died 31/8/1861) married Margaret Karran 26/1/1806 at Lonan and retired to Croit-e-Quill.
Had Thomas (b1806), Phillip (b2/2/1809, died 1852 Bendigo, Aust), Jane (b2.6.1811 - early death?), John (b 9/2/1815, died Aust), Jane (22/4/1817), William (21.6.1818) and James (15/7/1821) - all born Lonan.
Thomas (1782-?) thought to be son of Phillip Cowin (1729-?, Maughold) and Margaret ? married at Ballaugh 6/11/1770.
Does this help or further confuse?
Ross