There is indeed more, but it is posted on the Rennick forum, not this one. Look at messages 147, 148, 149, 150 posted by Richard Pangburn July 20-21, 2002, and my reply (message 151) on July 22, 2002. Joshua was not Moluntha, but a different Shawnee chief, Wryneck. The documentation for that identity is supplied by Richard, and (to my mind) incontrovertible.
It happens that your message came as I was reading S.C. Gwynne, Empire of the Summer Moon, a detailed account of the famous capture of Cynthia Parker in Texas in 1836 by the Comanche. She was another captive who would not leave her adopted tribe of her own will, though she led a much rougher life than Joshua. She was mother of Quanah, the most famous of the Comanche war chiefs.