public void Populate_source_records_from_records()
 {
     Source_records.Clear();
     foreach (var record in Records)
     {
         Source_records.Add(record);
     }
 }
 public void Add_record_permanently(TRecordType record_to_add)
 {
     Source_records.Add(record_to_add);
     Records.Add(record_to_add);
 }