#define LAYOUTFILE <MyProject/Small.lay>
#include <CtrlCore/lay.h>

struct SmallClass : WithSmallClass<ParentCtrl> {
	typedef SmallClass CLASSNAME;
	
	SmallClass();
	...
};

#define LAYOUTFILE <MyProject/Big.lay>
#include <CtrlCore/lay.h>

struct BigClass : WithBigClass<ParentCtrl> {
	typedef BigClass CLASSNAME;
	
	BigClass();
	...
};