I'm confused by your statement:
""Now getting back to the Galloway`s, Rebecca Galloway bore a daughter by Tecumseh, but they did not marry, she went to live with relatives.""
Where did you get this information? From my understanding the rumors of Tecumseh and Rebecca Galloway were fantasy. It was said that Tecumseh was in his late teens when Rebecca was still a small child. (no proof)
It was said that Tecumseh visited the Galloway family, not to see Rebecca, but because the Galloways were relatives of his mother.
" It is known that Capt. James Cross and Shawnee wife adopted Tecumseh`s baby daughter Shadrack Penn."
Where is this information, how is it known?