Parenting by name

Not using an expression but a script:

var proj = app.project;
var thisComp = proj.activeItem;

app.beginUndoGroup("Undo");
for (var i = 1; i <= thisComp.numLayers; i++) {
  if (thisComp.layer(i).source instanceof CompItem) {
    for (var j = 1; j < thisComp.numLayers; j++) {
      if (thisComp.layer(j).nullLayer && thisComp.layer(j).name == thisComp.layer(i).name) {
        thisComp.layer(i).parent = thisComp.layer(j)
      }
    }
  }
}
app.endUndoGroup();