In case you were wondering about possible confusion about the 2 William Costains born in Arbory circa 1812, the William Costain bap 23 Feb 1812 in the last message had a second cousin, William Costain bap 21 Aug 1814 Arbory, son of William Costain and Catherine Radcliffe.

JQ gives this info on the 1814 William:

40. WILLIAM4 COSTAIN (WILLIAM3, RICHARD2, JOHN1) was born 21 Aug 1814 in Arbory. He married ELZ CLEARY.

Children of WILLIAM COSTAIN and ELZ CLEARY are:

i. JOHN GLEAVE5 COSTAIN, b. 1844; m. JANE ALMOND.

ii. JAMES COSTAIN, b. 1846; m. SARAH ANN ?.