This is just a theory, based on 1861 and 1871 census entries plus IGI (including some patron submissions but there's nothing better to go on at the moment)
James Kelly bap 30 April 1851 St Mary's Castletown (pat sub), the painter who married Eliza Jane Costain 1st June 1878 Malew (ext), was with parents John Kelly 36, painter, and Jane 34 b Marown in the 1861 census. I believe that Jane was Jane Ritson (bap 27 Aug 1827 Marown and married John Kelly 27 May 1855 Malew) and that she was James's stepmother.
Looking in the IGI at the baptisms of all the children living with John and Jane in 1861 and 1871, the oldest ones may have been the children of John and Ann (possibly Ann Mylrea, married John Kelly 26 Nov 1844 Malew)
There's a burial of an Ann Kelly in 1854 Malew.
KELLY, Ann 34 Malew 10 Sep 1854
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Donna, please would you look in the burial register, and also see if there's an MI ?
Also for this one who may have been a son of John Kelly and Ann (Mylrea?):
KELLY, James 3 mos Malew 12 Aug 1846
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Below I'll attempt to paste in Ancestry's transcribed versions of the 1861 and 1871 entries for John Kelly, painter, and Jane in Castletown, plus the 1871 entry for James age 20 which shows him living nearby with a cousin.
Jean C
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1861 Isle of Man Census
about James Kelly
Name: James Kelly
Age: 10
Estimated birth year: abt 1851
Relation: Son
Father's Name: John
Mother's Name: James
Gender: Male
Where born: Castletown, Isle of Man, Isle of Man
Civil Parish or Township: Malew
Town: Castletown
County/Island: Isle of Man
Country: Isle of Man
Street Address: View image
Condition as to marriage: View image
Education: View image
Employment status: View image
Occupation: View image
Registration district: Anglesey
Sub-registration district: Holyhead
ED, institution, or vessel: 2a
Neighbors: View others on page
Household schedule number: 68
Household Members: Name Age
John Kelly 36
James Kelly 34
John Kelly 12
James Kelly 10
Robert Kelly 7
Joseph Kelly 5
Margaret Kelly 3
Philip Kelly 1
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1871 Isle of Man Census
about James Kelly
Name: James Kelly
Age in 1871: 20
Estimated birth year: abt 1851
Relation: Cousin
Gender: Male
Where born: Castletown, Isle of Man, Isle of Man
Civil parish: Malew
Town: Castletown
County/Island: Isle of Man
Country: Isle of Man
Street Address: View image
Condition as to marriage: View image
Occupation: View image
Disability: View image
Registration district: Isle Of Man
Sub-registration district: Holyhead
ED, institution, or vessel: 1c
Neighboors: View others on page
Household schedule number: 136
Household Members: Name Age
Catherine Teare 35
James Kelly 20
John Teare 12
View original image
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1871 Isle of Man Census
about Philip Kelly
Name: Philip Kelly
Age in 1871: 10
Estimated birth year: abt 1861
Relation: Son
Father's Name: John
Mother's Name: Jane
Gender: Male
Where born: Castletown, Isle of Man, Isle of Man
Civil parish: Malew
Town: Castletown
County/Island: Isle of Man
Country: Isle of Man
Street Address: View image
Condition as to marriage: View image
Occupation: View image
Disability: View image
Registration district: Isle Of Man
Sub-registration district: Holyhead
ED, institution, or vessel: 2b
Neighboors: View others on page
Household schedule number: 8
Household Members: Name Age
John Kelly 48
Jane Kelly 44
Joseph Kelly 15
Margaret Kelly 12
Philip Kelly 10
Anne Kelly 8
Thomas Kelly 5
Evan Kelly 2
Henry Kelly 2 months
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