Edit :
AP/C/4549 Will of William Colwill, yeoman, of North Petherwin 1810
Also X355/329 Copy inventory of goods, of William Colwill, deceased, North Petherwin , July 1810
search form Cornwall Archives
This presumably is the one buried in 1810(see below). He cannot be the father of your Eliza .It could name his children and perhaps other relatives and thus help exclude one or other William
I had a go at putting the births, marriages and burials of the two (three?) families together, sometimes you can manage to find a death which sometimes helps but unfortunately doesn't seem to this time. For what it's worth, heres the list. unless noted otherwise, they are baptisms. I've only put the year in most cases but the date is findable on the database Cornwall OPC I've included both Colwill and Colwell
1784 North Petherwin William COLWILL Mary MARTYN marriage Dec
1790 North Petherwin Thomasin COLWELL William Mary
1790 North Petherwin William COLWILL Mary TURNER marriage 5th Jan
1791 North Petherwin Grace COLWELL John Grace
1792 North Petherwin Mary Ann COLWELL William Mary
1793 North Petherwin Mary COLWELL Burial 7th January
1794 North Petherwin William COLWELL Mary PEARCE Marriage 25 Feb
1795 North Petherwin Elizabeth COLWILL William Mary 1st January.
1795 North Petherwin Mary COLWILL Burial 22nd July
1796 North Petherwin William COLWILL William Mary
1798 North Petherwin Jenny COLWILL William Mary
1800 North Petherwin John COLWILL William Mary
1801 North Petherwin Thomasin COLWILL burial 11 March
1802 North Petherwin Elizth. COLWILL William Mary
1804 North Petherwin Thomas COLWELL William Mary
1804 North Petherwin William COLWILL Burial 19th July
1805 North Petherwin William COLWILL Burial 20 June
1807 North Petherwin Grace COLWILL William Mary
1808 North Petherwin Eliza COLWILL Willm. Mary
1810 North Petherwin William COLWILL buried June
1810 North Petherwin Elizabeth COLWILL William Mary Dec
1811 North Petherwin William Tink COLWELL Mary SPETTIGUE marriage 3rd April
1812 North Petherwin Eliza COLWILL William Mary