Dear Mr. Captain,
Thank you for posting your request on History Hub!
The National Archives only has custody of records created by the federal government that document tribal nations during American nationhood, and often only details of those living on the reservations or being administered by the Bureau of Indian Affairs. Since the U.S. government did not interact with the Eastern Shawnee Tribe during the Colonial period, NARA’s records would not contain information about Tecumsah’s parentage.
We searched the Internet Archive catalog and located the book Tecumseh : a life. The book contains 21 references to Methoataaskee and has footnote references that can be further researched. Another book titled Life of Tecumseh, and His Brother the Prophet: … may contain information about the siblings of Tecumseh.
We also searched the Hathitrust catalog and located the book History of the Indian tribes of North America :with biographical sketches and anecdotes of the principal chiefs. … which contains a reference to Methoataaskee and the siblings of Tecumseh beginning on page 67.
We hope this is helpful. Best of luck with your research!
[Some information provided by Cody White, Subject Matter Expert]