I have been researching the John Pigman family of Charles Co/later Prince Georges Co. Md for decades. I just now saw where you have a study group and are offering to help!
Most Pigman researchers blindly follow the entry in the book "John Pigman and His Descendants" where it lists John Pigman's father as Ralph Pitman of Parndon, Essex, England and his father as Henry Pickman . This information is incorrect and I am trying to find the real origins. The earliest date I had for John Pigman until recently was:
Recorded on 12 September, 1695, John Pigman received a patent for 137 acres of land in then Charles and now Prince George's Co. from Col. James Smallwood, who had the original grant (HR Land Office, Patent BB#3 F-261, Certificate BB #3F-260)
From "John Pigman and His Descendants" by Kelleher, Funk, Witt, and Young:
"The 137-acre tract of land which John Pigman acquired and called "PARDON" cost him an annual rent of five-shillings, six pence. It was located on the Piscataway River at the mouth of Tuckoos stream in what was then Charles and is now Prince George's County. It would be in present day Clinton, on Steed Road between Piscataway and Allentown roads, less than five miles outside the southern boundary of the District of Columbia. It was John Pigman's home for the rest of his life and remained in the family for 20 years more."
The above is from the Pigman book and I believe Parndon was already named that when Smallwood owned it. Also, this land is just off the end of the runway for Washington Executive/Hyde Field Airport, Clinton.
A record of John Tigman in "Settlers of Maryland 1673-1700" by Peter Coldham Wilson. It shows a John Tigman as owner of a tract of 137 acres of land in 1695 called Paindon. The transcriber obviously erred in transcribing the capital cursive P and read it as a T. I can see how this happened. Additionally the Paindon transcription was obviously Parndon. Polly Kelleher, who researched the Pigmans, was trying to understand why she couldn't find John Pigman in the introduction from her book. She could not find him in the compiliation of the Early Settlers of Maryland. She couldn't find it because it was misspelled.
I recently found this:
Nov. 12, 1684 - Ordered that John Pigman and James Lyle servants to Mr. Edward Pye be free and have their corn and clothes from said Pye. (Charles Co., Md. Circuit Court, Liber L, p. 19.)
Also, familysearch has recently put up some records of Norfolk, England where several Pigmans are listed as early as 1620 in Hunstanton, Norfolk, England. I think he came from Norfolk, Eng as he was indentured to Col. Edward Pye who was associated with the Calvert (1st Lord Baltimore), and Cornwallis families (all associated with Norfolk and near Old Hunstanton) through his indenture.
Is your study group still working on problems such as this? I hope so!