>How can I add extra new rows in the listbox when is populated from a table (alias)?

In addition to what Ko answered, if you do not want to change table, you require to read table into listbox manually in the loop through table records using AddListItem and AddItem methods of listbox. Than you will be able to do anything with listbox items. You can try to use these methods with table too (I hope this works), but any requery of listbox will require to add these items again.