Am I right in thinking the line is as follows
1. William Vondy and Cath Kewin

Their children:
2.1 Thomas Vondy c1730 (married Ann Kermeen)
2.2 WILLIAM VONDY c1742 (married Margery Christian)

Their children:
2.2.1 William c1773
2.2.2. Elizabeth (aka Eliza) c1776
2.2.3 Thomas c1780
2.2.4 Margery c1785
2.2.5 John c1791

I'm researching Elizabeth, who I think I've found in the 1841 Census in Dale Street, Ramsey.
She has a young lad living with her who is recorded as Will'm Harrington. I believe his correct name is William Heatherington, and I'm in touch with his great great grandson.

Does this tree agree with yours?

David