Oh, my head is spinning!
A Ralph Caveen is mentioned in the Arbory 1837 will of Thomas Caveen.--will is online in Brian's Index Ralph is noted to be his brother.
"Fourthly I leave and bequeath to my two brothers namely John and Ralph
Caveen the sum of five shillings to each of them as legacy."

The various censuses would have Ralph being b abt 1791 in Arbory. If he is the brother of this Thomas, then the parents would be John Caveen and Elinor Quayle who md 25 Jul 1778 Arbory.

Just so I don't forget to post if this is relevant,
Thomas was md to Jane Cottier, didn't seem to have any children.
!DEATH: 11 Aug 1837 - Arbory Ancient Yard Monumental Inscription D33:
Blessed are the dead which died in the Lord. To the memory of Thomas Caveen of this parish who departed this life the 11th of August 1837
aged 55 years. He died in Jesus and is blest. How kind his slumbers are from suffering from sin released and free from every care.
Also to the memory of Jane Cottier wife of Thomas Caveen who died the 27th of January 1871 aged 81 years.

Jane was d/o Michael Cottier & Elinor Karran of Rushen.