Nonreving on direct flights on DL

So my parents and I are going to nonrev to Kona on DL since we heard it was going to be discontinued. On the way back, we want to take the through flight to ATL. I have heard stories where people on through flights get priority boarding over other nonrevs. I know there is going to be a big list for SLC-ATL and the flight is going to fill up and I know we aren't going to be first on the list (1998) so I really would like to know this. I have heard stories of buddies traveling ATL-LAX-HNL and the buddies who traveled the ATL-LAX portion got first on LAX-HNL while other employees got coach. Is this true??

if it is a direct flight with same flt number then yes, nonrev passengers boarded at orig station are higher on the nonrev list then nonrevs (using the same priority) who are trying to board the flight at a midpoint stop.