536. A Double Parsha

78:2 If a second Kohein or Levi was called up in the middle of the aliyos, then another Yisrael should take the aliyah in his place while the Kohein or Levi stands by. That Kohein or Levi should then be called for Maftir or for the final aliyah, after all the rest of the aliyos. (If this is not possible for some reason, then the Kohein or Levi should take the aliyah and not simply return to his seat – Mishnah Brurah 135:35)

78:3 On a Shabbos when two parshas are read, they are connected in the fourth aliyah.