Merging an Adjustment layer to many layers.

Try this script. You have to have the adjustment layer selected when you run the script! It will not merge with a smart object nor a group (layer set). It will only merge with layers that are below it, and that are in the same "group" such as the top level of the file, or in a layer set.

#target photoshop
var doc = activeDocument;
var adjL = doc.activeLayer
for(var i = adjL.parent.layers.length-1;i>0;i--){
    doc.activeLayer = adjL.parent.layers;
    var nextL = doc.activeLayer
    if(nextL.name == adjL.name){break;}
    if(nextL.typename !='LayerSet'){
        try{
            doc.activeLayer = adjL
            dupeL ();
            var tempL = doc.activeLayer
            tempL.move(nextL,ElementPlacement.PLACEBEFORE);
            mergeL ();
            }
        catch(e){
            tempL.remove()
            }
        }
    
    }
function mergeL(){
     var idMrgtwo = charIDToTypeID( "Mrg2" );
        var desc5 = new ActionDescriptor();
    executeAction( idMrgtwo, desc5, DialogModes.NO );   
    }
function dupeL(){
    var idCpTL = charIDToTypeID( "CpTL" );
        executeAction( idCpTL, undefined, DialogModes.NO );
    }