I married a guy who is the great grandson of Gustav and Elizabeth.
I have pictures of both of them on our family tree.
I also found a great book called "Portrait and Biographical Record of Shelby and Moultrie COunties, Illinois."
which has info on Elizabeth's father Jacob Galster which also mentions his parents Mathias and Rosanna (Haller)
This book also has information on Elizabeth Mautz's family via a section on her brother Jacob Mautz. Lists her parents as George G. and Margaret C. (Anger).
I have these documents saved in my family tree if you are interested in seeing them.