538. Not Enough Sifrei Torah

78:6 If one made a mistake on Shabbos and read from shishi (the sixth aliyah) until the end of the parsha, Kaddish is not then recited. Instead, Maftir is immediately called up and that will also count as shevii (the seventh aliyah). Kaddish is then recited after the haftarah and its brachos. (Mishnah Brurah 282:33 says that part of what was read for shishi should be repeated for shevii, followed by Kaddish and Maftir.) Similarly, if a mistake was made on yom tov and one read from revii (the fourth aliyah) until the end, Kaddish is not then recited. Instead, Maftir is immediately called up and after Kaddish is recited after the haftarah and its brachos. (See previous note.)

78:7 If we’re supposed to take out three Torah scrolls but there are only two, one should not roll the second in order to read from it in place of the third. Rather, the first scroll should be used. (If the first scroll has not been rolled to the proper place, then the second scroll should be used so as not to unduly burden the congregation – Bi’ur Halacha 669:1 s.v. v’chozrin.)