I suggest using the Process Screening platform and using the Grouping role.
Process Screening(
Process Variables( :NPN1 ),
Grouping( :lot_id, :wafer ),
Control Chart Type( "Indiv and MR" )
);
This will give you the statistics and analyses you want, but you will get a separate control chart for each level of the grouping variable rather than 2 control charts with phase variables.