Hi,
Re Nancy Jenkins,
Family search records show Thomas Martin married Nancy Jenkins 1st Jan 1825.
Records show births of
thomas (my gggf) Nancy (jnr) Elizabeth, mary.
Nancy Martin (jenkin (s)) as per census born St Keverne between 1791 and
1802 depending on which census you believe.
As there is no record of her being born in St Keverne and going by the age discrepansy, it is even possible she did not know wher she was born.
Nancy Martin (jnr) married John Bray and had several children
James named after john's father
Thomas Martin Bray named after Nancy's father
Lazarus Jenkin Bray, so where does this come from

?
Theoretically after Nancy Martin's (mother of Nancy Bray's) father or brother
I can find no record of Lazarus Jenkin that could be father of Nancy Martin.
There is a Lazarus jenkin 1861 Census age 46, location Vessel, so assume he was a mariner, born 1815 in Kea. Records show he married Sep 1862, Truro (near Kea) died Perranarworthal or Helston depending on which records to believe Dec 1862. Shows married life did not agree with him.
He was too young to be father of Nancy Martin (jenkins) but could have been son of Nancy's brother if he existed.
Regards
Peter Martin