Thanks for much for the information on Phoebe and pointing out about Amy too. And for the marriage suggestion.
Also I have found this Kent parishes index on familysearch, which I hadn't seen before that includes burials for Westerham:
https://familysearch.org/search/collection/1952887I have also had a look at the Westerham baptisms transcribed on findmypast which include some not on familysearch, including John's 1799 baptsm.
From these I now know the following about the two Wicken couples which most directly link with my adoptive line:
The children of Thomas Wicken and Mary:
Charlotte Wicken/Still 1798–1872
John Wicken 1799-1875 (baptised as Wickens)
Rebecca Wicken 1801-? (baptised as Wickins)
James Wicken 1804-?
Henry Wicken 1806–1848
Sarah Wicken 1808–?
Samuel Wicken 1809–?
Phoebe Wicken/Peacock 1811–1894
Harriet Wicken 1813– 1813
Rebecca and James are newly discovered siblings and along with Sarah and Samuel, I know nothing of what became of them.
And not sure of Thomas and Mary's marriage in c1795-1797 or the couples origins, other than they were NOT born in Kent (according to the 1841 census).
The children of Thomas' son John Wicken and Charlotte Sales:
Sarah Wicken 1821–1821
Jane Wicken/Nixey 1822–1878
Phoebe Wicken/Brown 1824–aft 1845
John Wicken 1826–1848
James Wicken 1828–1865
Mary Ann Wicken 1830–1832
Sarah Wicken 1830–aft 1841
Ann Wicken 1833–aft 1841
Hannah Wicken/Record 1834–1921
William Wicken 1838–1867
Emma Wicken/Beavis 1840–aft 1891
Charlotte Wicken/Lingwood 1843–aft 1881
So it is Phoebe, Sarah and Ann who are the mysteries in this batch of Wicken children.
The family actually lived at Crockham Hill in Westerham and I have found tonight a newspaper article staing that in 1838 John Wicken, a blacksmith and farrier, was in a debtors prison.
Again, thanks for all the information,help and guidance in my Wicken quest.
Jon