That is excellent advice to first look at US records.
I couldn't see wills for Patrick Caley's assumed parents at the dates of their burials, but siblings are always a possibility.
I didn't find Patrick in later censuses, and think he left the IOM between 1841 and 1851.
The siblings are a problem because there were another two couples in Maughold called John Caley and wife Isabella having children baptised, and two of the Isabellas were Isabella Corkill!
John Caley & Isabella Corkill no.2 married in Maughold on 7 Mar 1835, so the bapts after that are probably theirs. This family was from Port y Vullin, Maughold.
The first couple probably married in Andreas on 20 May 1802.
These are the Maughold bapts:
William [son of] John Caley & Isab Corkill [bapt] Parish Church 13 Jun 1818. Private baptism
Margaret [daur of] John Caley/ Isab Corkill [bapt] Parish Church 29 Apr 1827
Isab John Caley/ Isab Corkill Parish Church 7 Jun 1835
John John Caley/ Isab Corkill Parish Church 22 Jan 1843
Esther Ann John Caley/ Isab Corkill Parish Church 29 Mar 1846
Paul John Caley/ Isab Corkill Parish Church 14 Jan 1849
Mary Ann John Caley/ Isab Corkill Parish Church 1 May 1853
Ewan John Caley/ Isabel Casement Parish Church 18 Jul 1808. Private baptism.
Esther John Caley/ Isabel Corkhill Parish Church 9 Jul 1815
Ewan John Caley/ Isabel Corkill Parish Church 3 Jan 1803. Private baptism
John Ned John Caley/ Isabel Corkill Parish Church 24 Feb 1805
William John Caley/ Isabella Parish Church 17 Nov 1850
Patrick John Caley/ Isabella Corkill Parish Church 26 Nov 1820
Edward John Caley/ Isabella Corkill Parish Church 2 Feb 1824
Elinor John Caley/ Isable Corkill Parish Church 15 Jul 1811. Private baptism
So Patrick's probable siblings, apart from William bapt 1818 & Margt bapt 1827 who we already know about (because with their mother in the 1841 census), were Ewan bapt 1803 (Ewan CALEY infant buried Apr 20 1803), Ewan bapt 1808 (Ewan CALEY infant buried Jul 25 1808), John Ned bapt 1805, Elinor bapt 1811, Esther bapt 1815, and Edward bapt 1824.
I found William in the 1851 census still in Maughold, in Lewaigue, aged 32, lab., with wife Judith 46, sons William 6 and Patrick 3, and step-son Thomas Corkill 12.
Thomas Edward Illegitimate son of Thomas Corkill & Judith Cleator bapt Maughold 9 Dec 1838.
William Caley & Judith Cleator married in Maughold 28 May 1842.
Judith CALEY ag. 49, Lewaigue, buried Maughold 7 Mar 1854.
I didn't find William or his two sons in the 1861 IOM census.
Nor did I find John Ned Caley bapt 1805 in IOM censuses, or Edward Caley bapt 1824. The 1880 US census has an Edward Caley aged 58, b.IOM, tailor, in Sherburne, Chenango, New York, who looks a possibility?
Sue