...
type
TNew = class(TOld)
  private 
   aData1:Variant;
   aData2:Variant;
...
   aDataN:Variant;
  public
Constructor Create(aOwner:TComponent);overload;override;
Constructor Create(aOwner:TComponent; 
                           aValueForData1, ..., 
                           aValueForDataN:Variant);reintroduce;overload;
...
end;


Constructor TNew.Create(aOwner:TComponent);
begin
  inherited Create(AOwner);
  < чё-то там еще >
end;

Constructor TNew.Create(aOwner:TComponent; 
                                   aValueForData1, ..., 
                                   aValueForDataN:Variant);
begin
   Create(AOwner);
   aData1 := aValueForData1;
...
   aDataN := aValueForDataN  
end;

...