For tedious expressions that I am going to be using all the time I save them as animation presets. Instead of a layer name you can use index-1 to indicate the layer above.
If I saw the timeline and knew exactly what you were doing I could give a better answer.
Hey Rick! That might work. Little new to expressions, How do you save the expression as an animation preset?
That index-1 might do the trick.
Basically i have this setup repeated in my comp 48 times
so I need to link the particular position to the null position and each Rotation axis to the null orientatoons.
Thanks for for your help
Basically, do what Rick said. On your first layer, pick whip to the null's position, orientation, etc. to get it working. Then, in the expression, replace it's reference to the layer itself with the index -1 or +1 (depending on how you want to structure things). See if it still works. If so, great! Just duplicate the layer and move it in the layer stack.