I just looked around quick for a Lena Mueller and found a short obituary. She died near Brighton on M-street where Max lived. The Newspaper has her full name as Lina Emilie Mueller.
I wonder if the Amelia Mueller from the Fritz obituary is a misspelling of Emilie.
The Fritz and Mary deaths also would explain why there is such a large age gap between Anna and Julius.
New names to start adding to my search.