Yevamot 119: Starting with Co-wives, Ending with Co-wives

Starting the last chapter of Yevamot... A woman travels with both her husband and a co-wife, and when she returns, the claim is made that her husband died. Can she marry, or does she have to do yibum? But what about the impact of the co-wife? What if the co-wife is pregnant (and then there would be no need for yibum)? Similar questions arise with regard to other comparable demographics. At the end of the day, the likelihood of pregnancy implies that there is no yibum. Thus, defining "majority," and exploring its implications. Also, the case of 2 yevamot and what happens for each woman when the other claims that her husband has died? The slim chance that the husband is alive leaves them each in limbo as potentially needing yibum. Similarly, the case of witnesses to a husband's death - but what of the death of the yavam? Parsing out the cases, depending on who is in which position, etc. - for example, waiting for confirmation to the death. But what if there are other brothers? Potential yevamim. Which leads to applying all the different concepts and terms throughout.