I do not know if you found the names you are looking for. But living in Illinois, I searched here and found her grave, which you probably already have.
www.findagrave.com/memorial/23914475/mahulda-jane-campbell
I also found a 1850 census for Waukegan, Lake, Illinois
with George Craig as the father - 57
Maria - the mother 47
Mary - 27
Mercy - 18
Jane - 16
Caroline - 6
George 6
I hope this helps you out!
Good luck with your search.
https://www.familysearch.org/ark:/61903/3:1:S3HT-63K7-WPK?i=16&cc=1401638