Maintain the correct zones

[#1]

On the control charts, I want to exclude the zones over the average when there is no lower limit. 
Here is my script : 

        // Loop across the split data table and read the values for that column from the dt_limits_copy data table. Populate the Spec Limits and Control Limits
For(i = 1, i <= N Cols(dtsplitcopy), i++, 

	limrow = Try((pIDlimits_copy << get rows where(pIDlimits_copy:labelny == cols[i]))[1], .);

	If(Is Missing(limRow) == 0,
		specs = {LSL(.), USL(.), Target(.), Show Limits(1)};

		specs["LSL"] = pIDlimits_copy:Lower Limit Value[limrow];
		specs["USL"] = pIDlimits_copy:Upper Limit value[limrow];
                   
		Column(dtsplitcopy, Char(cols[i])) << set property("spec limits", Eval(specs));

		controllimits = {Individual Measurement(Avg(a), LCL(b), UCL(c))};
                   
                    // If lower limit is missing it is set to mean - (UCL - mean) = 2*mean - UCL as this will fix issues with zones otherwise being wrong if set to missing
		Substitute Into(controllimits,
			Expr(b),
				If(Is Missing(pIDlimits_copy:Lower_Control_Limit[limrow]),
					2 * pIDlimits_copy:Mean_Plot[limrow] - pIDlimits_copy:Upper_Control_Limit[limrow],
					pIDlimits_copy:Lower_Control_Limit[limrow]
				)
		); // this is done to get correct zones
		Substitute Into(controllimits, Expr(c), pIDlimits_copy:Upper_Control_Limit[limrow]);
		Substitute Into(controllimits, Expr(a), pIDlimits_copy:Mean_Plot[limrow]);
                   
		Column(dtsplitcopy, Char(cols[i])) << set property("control limits", Eval(controllimits));
                    // These notes are added so that later we can choose to hide the "artificial lower limits" which is only included for the zones to be correct
		Column(dtsplitcopy, Char(cols[i])) << set property(
			"notes",
			If(Is Missing(pIDlimits_copy:Lower_Control_Limit[limrow]),
				"Only one limit",
				"Two limits"
			)
		);
	);
);
       
dtsplitcopy << sort(by(Date), Replace Table);

n_vars = N Items(cols);
        // Create window for a control chart for all parameters of a given product from a given site
NW = New Window(sitename || " " || prod_ID || " Report",
	For(v = 38, v <= n_vars, v += 1, //changed from column 37 to 38 to avoid 'Date' being printet as well.
               
		tmp = :column(v) << get property("notes");
               
		Control Chart Builder(
			Show Two Shewhart Charts(0),
			Show Control Panel(0),
			Include Missing Categories(0),
			Name("AIAG (Ppk) Labeling")(1),
			Variables(Y(:Column(v))),
			Chart(
				Points(Statistic("Individual")),
				Limits(Show Lower Limit(tmp == "Two limits"), Sigma("Moving Range"), Zones(1)),
				Warnings(Test 1(0), Test 5(1), Test Beyond Limits(1))
			),

		);
	);
           
	vlb = V List Box(ob = Outline Box("Cpk estimates and print of data"));
);

What should I add to my script ? 

[#2]

*below the average not over the average . 
example : 

Here you can see that there is no LCL, thus i want to remove the zones below the green line, but i want to keep the zones above the green line. Also, when i have points on the A zone below the average, I don't want to have alerts because there is no LCL. Does someone knows how to do it? 

[#3]

I think this would require to you script those zones and shaded zones (it might be easier to do this in Graph Builder rather than in Control Chart Builder)