I am not sure what you would like to have sorted from A-Z then.
The first query in the last post would sort all names first by lastname (Resulting in a block with and one without lastname, within each subset the names sorted by firstname):
Angelina
Pete
Suzie
Joe Jolie
Pete Peterson
Susanne Zubeku
The second should give you all names sorted by firstname, when two firstnames are the same, the lastnames are sorted.
Angelina
Joe Jolie
Pete
Pete Peterson
Susanne Zubeku
Suzie
Please show me the output you do get, and the one you would like