While I cannot provide definitive information about your Isaac and Elizabeth Penfold, I can tell you that Abraham Penfold of Posey Co, IN and his son Abraham (m Elizabeth Wells Posey Co In 1832) were both born in England. The Wells family also had many members who lived in Edwards and Wabash Co, IL. I would suspect that they were of the same family. Abraham Sr died in Posey Co in 1826. Availability of probate records in that County is rather hit or miss at present, but you might try writing to Nancy Mathew, the Genealogy Clerk in the office of the County Clerk in Mt Vernon, Posey Co, IN. There is a nominal fee for her research and copy time, but she is very thorough and if there are records available she will find them. Good luck.