Yes I follow your theory, I have been working on the same lines trying to link the Downings and Kelynacks. I have found in the IGI Kelynack-Downings going back to 1811 and working my way up.
Stephen Downing B 1778 and Mary Kelynack B 1780 married in1807.They had children
1) Phillis Kelynack Downing B1811 who married William H Badcock.
2) Stephen Kelynack Downing B 1809 No spouse as yet
Henry Downing B 1824 married Charlotte Kelynack Downing 1849
Not sure if Stephen and Mary are his parents as his birth is 14 years after Phillis, but the IGI did say his father was stephen. Anyway Henry and Charlotte had a daughter Charlotte Mary B 1852 and a daughter Mary B 1850. not found any spouses for them yet.
This is how far I have got at the moment. Next I will try and link Simon Downing and Elizabeth Curnow into the family.
It is really like starting another family tree and linking the two trees together. As you say there are alot of if's and but's here.
I also read this article on birth certificates
Birth Certificates
Births weren't always registered. That only first became necessary on July 1st 1837, when it was decreed that every subsequent birth, marriage and death in England or Wales had to be registered by the state. With births, the event would be registered in the district where the child was born, and at the end of each quarter, the registrar would send a copy of all the entries to the Registrar General. That means there should be two entries - one local, one national - for every birth since 1837. However, registering all three events didn't become compulsory until 1875. When it was introduced, the cost of a copy certificate was two shillings and sixpence (30p), one shilling (5p) of which went to the registrar and the fee stayed the same until 1952.
This means that tracing births back to 1875 is relatively straightforward. Between 1837-1875 it might prove a bit harder, as some didn't register, or even gave false names for a number of reasons - to hide the true age of a child so it could be sent out to work, or, after 1853, because parents wanted to avoid the compulsory vaccination of children at three months old, which was introduced that year. Until 1875 there was no penalty for parents who didn't register a birth, and then a £2 fine was introduced.
http://www.exploregenealogy.co.uk/BirthCertificates.cfmAlso an excert from another article
In fact, over the next hundred years, the General Register Office
made remarkably few changes. Here are three examples of the minute
changes it did make: (1) it changed from handwritten to printed
indexes, (2)
registration became obligatory in 1875), and (3) a
mother, when reporting an illegitimate birth, could not name the
father; he had to be present and consent to his name being entered
James Downing Runnalls birth might not have even been registered as it was before 1875 the year it became compulsory.
Well I am going to get back to some more research
