TSimple = class(TPersistent)
published
 property One:integer read... write...;
 property Two:integer read... write...;  
end;

TMyComponent = class( TPanel )
 ...
published
 ...
 property Simple:TSimple read ... write ...;
 ...
end;  

TSimpleProperty = class( TClassProperty  )
public

   procedure Edit; override;
   function GetAttributes:TPropertyAttributes; override;
   procedure GetProperties(Proc: TGetPropProc); override; // НЕ ПОНЯЛ, КАК С ЭТИМ РАБОТАТЬ: вроде как нужно ...  
End;

procedure TSimpleProperty.Edit;
begin
 inherited;
 ?????????
end;

function TSimpleProperty.GetAttributes: TPropertyAttributes;
begin
 result := [ paMultiSelect,  paSubProperties ];
end;

procedure TSimpleProperty.GetProperties(Proc: TGetPropProc);
begin
 inherited;
 ?????????
end;