Yevamot 111: Minor Wives and Yibum (or Divorce)

1/3 of the way through the Talmud!! Another daf with 2 mishnayot, one long with little Gemara, one shorter, with a lot of Gemara. First, another case of 2 orphan minor girl's who are married to one man - what happens when the yavam sleeps with both of these potential Yevamot? And other comparable cases (deaf-mutes again, etc.). Also, a mishnah on divorce with these minor wives - which must wait until they are older. Likewise, what about an unconsummated yibum? Before or after 30 days? Which opens the discussion on the implications and timing of consummation and seclusion.