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Gibel has asked me to check in the LRO - St Bridget's Wavertree has the baptisms in original form so you would need to make an appointment to view them, emailing is the easiest way
https://liverpool.gov.uk/contact-us/service-area/liverpool-record-office/ . 

However, marriages are since 1902, original form go up to 1945. 

If the church is still in existence I would ask them if they hold the recent registers there.

One entry has his birth      Birth abt 1780 in Cork Ireland and  Death 22 May 1832 in Berbice, Mpumalanga, South Africa, occupation Protector of Slaves in various British colonies.

Sophia's baptism on 10 March 1782 at St Sepulchre, Holborn, London gives date of birth as February 11 or 14.  Parents Thomas Chandler and Sarah.

Another tree has      Birth 23 Sep 1754, baptism 20 October in St Sepulchre Holborn, London, England and     Death 1832 in Berbice, Guyana.  Parents listed this time are John Power and Mary Hayward

Another tree has David's son as
Edward Rawdon Bingham Power     Birth abt 1812 in Thames Ditton, Surrey, England     Death 4 Aug 1886 in Heywood Lodge, Tenby, Pembroke, Pembrokeshire, Wales and marriage to Ellen Louisa Stone June 1863 in Middlesex.

Another tree has their son as     

Thomas Charles Chandler Power     Birth 1819 in Cheshunt, Hewrtford, UK.     Death 1876 in Colombo, Sri Lanka. and married Eugenie Elizabeth Curgenven in 1845 Colpetty, Columbo, Ceylon.

None of these should be taken for granted without doing your own research.

There are no specific details as to addresses

That's a shame, was hoping to check the address.  Had no luck so far sorry.

Many documents open in Google docs if you have a gmail account, email it to yourself there and try it.

Later she is single and still at home with a bunch of siblings and widowed father.  Assuming you may have a subscription, check the name Owins rather than Onions.