Good thinking John. It explains why I couldn't find Lavinia King in 1851!
Not sure who her parents would be, but if she were the daughter of Charlotte her mother would have been only 11 when Lavinia was born, a tad on the young side. Ah! The figures are bad in 1851, and have been mistranscribed by Ancestry. I think she was 30, not 20, and William was 29 not 23, which makes your theory work.
You know it doesn't take much to confuse me these days John. The 1847 burial in Pulloxhill was Lavinia TAYLOR not King.
But guess what? In 1861 James and Lavinia Letting were living in the same house as William & Charlotte Taylor! Shown as a separate household, rather than son in law/daughter, but I don't believe in coincidences.
So what you're saying is that Lavinia King who married in 1861 was actually registered at birth as Lavinia Taylor, which would imply that her father was William Taylor. Whilst I'm sure that Charlotte King was Lavinia's mother, I'm not entirely comfortable with William Taylor being her father, given the blank for father on her marriage cert and the fact that she used the name King. It would take an investment of £9-25 to buy her birth cert to prove it.
None of the three daughters appear to have been baptised, either as King or Taylor. (Having said that I now see that Westoning baptisms on the IGI only go up to 1812, so reference to the microfilm is needed) - OK John, this really is my final modification!