Elizabeth Christian Cowin who marries Robert James Archer is the child of Thomas Cowin (b1776 of Langahan Onchan.) and Jane Christian. The 1851 census confirms this
1851 census
Onc 4 30 55
Langayhyn Cottage
Thomas Cowin head wid 74 Landed prop & retired farmer Onchan
James bro wid 61 Schoolmaster "
Thomas nephew s 10 Scholar Jurby?
Robert Archer son-in-law m 28 Joiner Onchan
Elizabeth wife m 30 Onchan
Thomas and Jane are married in 1803 and do not appear to have a John. Thomas dies in 1854 and his will is online at FamilySearch. It lists his living children and there is no John mentioned.