Middle Names and Memorials in Croatia

On Deb's trip to Croatia last October, she discovered two World War II (WWII) memorials.  One was in the town of Jošan and the other in Kurjak.  The memorial in Jošan is located next to a worn down church.  The church is presumably Serbian Orthodox.  Here is a picture of the church and of the broken down memorial and field next to it.  The field might have at one point been a cemetery which was destroyed during WWII?

Deb's brother Kendrick and her father, Earl, helped to overturn all the fragments of the memorial in Jošan that they could find.  Although they did not find any family names (Kljaić, Ilić, or Đaković), they took pictures of all the fragments and pieced together what the memorial once said.  (UPDATE: The full memorial is now given in a new post.)

             
The next WWII memorial in Kurjak had several family names.  Fortunately this memorial is still intact, and a picture of it is shown below. 

After finding both memorials, Deb was excited to discover that all of the names had middle initials with them!  Perhaps these middle initials would help us to distinguish one Jandre Kljaić from another.  But Lidija Sambunjak, a professional genealogist in Croatia, told Deb that Croatians do not have middle names. 

            
 So why do all these names on memorials seem to have middle initials?  Lidija said that memorials often list the first letter of the father’s first name next to the person being remembered.  Take the example below:

"Basta M Marko" was the brother-in-law of Jandre Kljaić.  The first name of Marko's father was Mile.  So the M in "Basta M Marko" stands for "Mile."
          
If Croatians don't have middle names, however, then how did Andrew John Klaich get the middle name of John?  The simplest explanation is that Andrew made up the middle name of John when he immigrated to the United States.  This corroborates with the fact that Mira, the niece of Andrew, said Andrew’s birth name was Jandre and that he didn't have a middle name.  This does not explain, however, why Andrew (or Jandre) would choose to adopt the middle name of John.