Complex sentence: At the very day the German Union was approved on October 3rd, 1990, the emblems of the "new" federal states were added, even as the areas which were now under Polish administration were finally ceded to Poland.
Split into simpler sentences: At the very day the German Union was approved on October, 3rd 1990, the emblems of the "new" federal states were added. Besides, the areas which were now under Polish administration were finally ceded to Poland.