merge.cs

using (MailMerge mm = new MailMerge()) {
  mm.TextComponent = textControl1;

  // attach events
  mm.BlockMerging += Mm_BlockMerging;
  mm.FieldMerged += Mm_FieldMerged;
  mm.BlockRowMerged += Mm_BlockRowMerged;

  // merge template
  mm.MergeJsonData(jsonData);
}