Set Layer Control ("Layer") in extendscript

After Effects/ExtendScript Geniuses,

Heres my dilemma, I've just started coding and I'm struggling to learn all the language/syntax. I need to figure out how to set the ("Layer") of ("Layer Control") that I've renamed to "A-Target" currently in Null4.property upon script launch.

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var mainComp = app.project.activeItem;

var tarA = mainComp.layers.addSolid([0.5, 0.5, 0.5],"B-Target", 480, 270, 1.0);

var Null4 = mainComp.layers.addNull();

Null4.name = "Camera Rig Controller";

var tar1 = Null4("Effects").addProperty("Layer Control");

tar1.name = "A-Target";

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All of the code above seems to work just fine. I just need to set that Layer Control layer to tarA

I've pretty sure it has to be something close to this:

tar1.property("Layer").setLayer(tarA)     -------> What is the right way to say this?

Many Thanks,

Sam