There are still too many open questions. In the 1870 census for Portsmouth, Ohio there is a Cora Shellieg (8) living with a William (49) and Jane (36) Shellieg. There is also a Willi (4) Shellieg.These could be her parents.
In the 1880 census there is a Cora Shellieg (18) in Covington, Ky living with the Warnfords.I am assuming they are the same person.She is not using the name McCollister.Why?When she married, what name did she use?
If she is the same person mentioned in the death notice, she married after 1880 and her children were born in the 1880s. She died before she turned 28.
It would be nice to find some other document showing that her father's name was McCollister.