There are a number of links between people that I suspect but that I don't have any real proof of. If you have any information about these or any other Ninehams, please let me know.
The last record I have found for Henry Nineham (b. 1723) from Corfe Castle is the baptism of his daughter in 1748. Then Thomas is baptised in Thanet in 1752, also with parents Henry and Mary. I am hoping there is a settlement record in the Kent archives somewhere to show where this Henry and Mary came from.
Robert Mary (nee Dugdale) Nineham had two sons John and Richard for whom I have no records after their baptisms. Then a few years later a John and Richard are marrying and having children in Cowes. They may have come from an earlier island family, but could easily have come across the water from Purbeck.
I need to do more work on this link. At present I have no firm evidence for it, just some names which match across generations. But as always, I have a number of alternatives that could be possible.