Hi Richard, I did find an entry for your grandmother's sister! It appears she died from scarlet fever. Here is what the entry reads:
Sutton, Alice Color: W, Age/Sex 2 y-F, b. US; d. 11 May 1919, scarlet fever, City and County Hospital, Loc: L3 G34, Buried 13 May 1919, Book B #1202
As far as I know there is only one grave in the cemetery that is marked. I grew up that area and have driven by it many times. You would not even know that there is a cemetery there - it just looks like a small field. I have no idea whether they will install markers or relocate remains.
I suggest you contact the Maplewood Historical Society for additional info about the poor farm
http://www.maplewoodhistoricalsociety.org/The Minnesota Historical Society is also a great resource for genealogy researchers:
http://www.mnhs.org/Good luck!
Threse McCarten
Minneapolis, MN