I should not have jumped to the conclusion they were not part of Jeremiah's family so quickly. I was unaware of any daughters born to him with his first wife Susan, or second wife Eliza Lines. Further research shows there were in fact 4 females under 16 in his household in the 1841 census. I have idea who they are and know nothing about them. I wonder if one of them is your Ellen? :-) Census is here
http://www.ontariogenealogy.com/emily/emily1841.txt