You're right about the death year discrepancy in this MI for Ann Christian, Philip.

Maughold Old Yard
A 62
In memory of JOHN CHRISTIAN of Ballaterson who departed this life the 13th Nov 1861 aged 65 years
Also ANN CHRISTIAN sister of the above who died September 11th 1891 aged 75 years

The burial register says:

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CHRISTIAN, Ann 75 Mau 15 Sep 1881

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Looking at the scenario of the acknowledgement and acceptance by James and Margaret Joughin of their dead son's child, Emily b 1851/2, I've been wondering whether the pregnancy was far enough advanced at Robert's untimely death in Sept 1851 for Emily's mother to be welcomed into the bosom of the family and encouraged to become one of the family ---- in which case Margaret (illegit dau of John Christian) would fit the bill nicely, as you'd have a logical explanation for Emily's middle name of Christian and an ideal set up for Emily's mother to become James's second wife soon after the death of Margaret nee Crowe in 1858.

On the other hand, if say the pregnancy had hardly begun when Robert died, so that he hadn't had chance to acknowledge the baby as his, it's easy to imagine that James and Margaret might be sceptical about the claims of a girl turning up on their doorstep saying she was carrying their dead son's child. Perhaps it was only as the child grew that a strong similarity in appearance to Robert convinced R+M that this was indeed their grandchild.

Probably pointless conjecture, but the fly in the ointment with scenario (1) is that Emily Kelly didn't describe herself as "daughter" on the death of James Joughin's second wife.

Is it possible that Margaret Christian's role during the 1850s prior to her marriage to James Joughin, was as servant/nursemaid/governess to Emily, supposing that the baby had been left with the Joughins by her birth mother. This might be an explanation for Emily's middle name of Christian, as Margaret would have been a sort of surrogate mother.

Ann Morrison is still a possible contender for the role of Emily's mother. There were 3 Emily Morrisons born in 1851-1853; the 2 who weren't illegitimate turn up in future censuses living with their birth parents, but there's no sign of an illegitimate Emily Morrison b 1852.

Jean C