This week we will continue learning about the 15 women that are  prohibited to do Yibum or Chalitza due to familial relationships. Not  only are they forbidden from doing Yibum and Chalitza but so are their  co-wives. The next Mishna teaches that there are 6 women who are closer  to the man than the original 15. These 6 women are also forbidden to him  but their co-wives are permitted to do Yibum or Chalitza.