Hi Andrea, sorry I'm late in replying but I've been busy.
My records seem to show that James C (ch 18 Sep 1743) married Margaret Faragher on 23 June 1765 in Marown. As you say they had 10 children ending with Charles who is recorded as being christened 17 July 1791 at Marown ( Film Number: 457959) and Lezayre ( Film Number: 442421 Page Number: 0074 Reference number: 2365)
I have a photocopy of James C marrying Catherine Kneale on 23 June 1792 from Lezayre Parish Register.
They had 3 children James (1793), Catherine (1795) and John (1797).
Our John (1783) from the first marriage married Ann Corlett (1787) at Lezayre in 1808.
James appears to be the first Cretney to travel to the north of the Island and set up a community there with his family moving with him.
Margaret C appears to have been buried on 23 Jan 1823 at Lezayre - there must be a story there somewhere.