Yes I do have an Isabella Sarah FENTIMAN (close enough), christened 16 May 1850 Dover, Kent; father Frances; but this information is based on the IGI and the Ancestral File - not entirely reliable. I just tried to confirm her in FreeBMD, without success - but the second quarter of 1850 Births is not completely transcribed yet, so that doesn't really prove anything one way or the other.The Ancestral File has her marrying Jacob L. Lantz 19 Oct 1865, Du Page County, Illinois, USA; if she was christened as an infant (which the vast majority in England at this time were) she would be only 15 then. I have no other trace of her in England. I have no other Fentimans known to be in Dover, but plenty in Kent - my line.
Another person with an apparent interest in her ancestry is Scott A. Grostefon - I have an e-mail address, don't know if it's current. E-mail me on @ntlworld.com- replace with roger.fentiman - if you want it.