Hi Marie

If your John Molyneux was a printer, this is the most likely marriage for Ann Jane’s parents (given that this couple gave the middle name Stewart to their 1851-born son):

Name: Anne Stewart
Gender: Female
Age: Full Age
Marriage Date: 14 Apr 1845
Marriage Place: Liverpool, St Catherine, Lancashire, England
Search Photos: Search for 'Liverpool, St Catherine' in the UK City, Town and Village Photos collection
Phillimore Ecclesiastical Parish Map: View this parish
Father: R S Stewart
Spouse: John Molynuex

Note:
Image shows:
JM full age bachelor/printer/Liverpool/father John Molyneux, butcher.
AS full age spinster/Liverpool/father R J Stewart, book binder.
Both signed.
Witnesses: Robt J King, John Macquilliam and Hannah Mary Cubbin.

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Baptism of a younger sibling of Ann Jane Molyneux:

Ancestry’s transcription:

Name: Charles Stewart Molyneux
Age: 0
Birth Date: 21 Aug 1851
Baptism Date: 21 Sep 1851
Baptism Place: Liverpool, St Peter, Lancashire, England
Search Photos: Search for 'Liverpool, St Peter' in the UK City, Town and Village Photos collection
Phillimore Ecclesiastical Parish Map: View this parish
Father: John Molyneux
Mother: Ann Molyneux

Note: JM printer.

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Ancestry has transcribed the 1851 census for Ann’s family like this:
Name Age
Ann Nwlynew 32
Ann J Nwlynew 5
Eleanor Nwlynew 3
Jane Nwlynew 28
Elizabeth Beattie 19
Mary Ward 14

Note:
Ann Molyneux married, wife of Printer / compositor, b IOM

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In 1851, John Molyneux (printer) was in Douglas, staying with his brother Samuel’s family.

Jean C