Oh, thanks for linking to that blog post. As I explain in one of the comments, that was quickly written in reply to some internet content that consists of people reading an online article or two and then making unwarranted conclusions and criticisms about things they know little about.I most certainly agree with Amy. It is not unusual, as you investigate your ancestors who were early members of The Church of Jesus Christ of Latter-day Saints, to find men who appear to have "extra" wives that were not acknowledged or documented by the traditional genealogy you may have received from an aunt or grandmother. This is a delicate topic and made more difficult by the proliferation of blatantly anti-Mormon literature on the subject. Fortunately, current policy of the Church includes directly confronting those issues. You can see this on the LDS.org website section on Gospel Topics. The Gospel Topics article addressing part of these issues is entitled, "Plural Marriage and Families in Early Utah." Further accurate historical information can be obtained from websites such as FairMormon.org.
WIlford Woodruff was instrumental in our current temple practices, in Nauvoo, in 1870s St. George, and later in the 1890s when he ended the practices of plural marriage and (priesthood) adoption.
Anyone who's involved in 19th-century Mormon genealogy should understand those practices and how they show up in church databases as sealings of your ancestor to someone outside the family or "extra" marriages to unknown women. Even though the practices have changed, those are important pieces of historical information and should be preserved in church and family records.
From a genealogical standpoint, anyone with ancestors who were early members of the Church during the time plural marriages were being performed, may have family members who were part of a such a family. In addition, there was another practice that impacts genealogical records but did not involve actual physical marriages between husbands and wives. Unfortunately trying to untangle this practice from the inaccurate haze of anti-Mormon statements, accusations and outright lies is very difficult. In some cases, women who died before they married were sealed to men, sometimes a prominent leader of the Church and also to family members. In addition, occasionally a living woman who was in need of support would also be sealed to a man as a plural wife so that she could be supported. Both of these conditions exist in my own family lines.
Genealogists who encounter these situations have tended to discount them and even refused to enter the information into the genealogical records they created. However, as Amy states above, these are important pieces of historical information and should be preserved in church and family records. I have been asked about these marriages a number of times and usually, the person asking the question is disputing the existence of such a marriage that is only evidenced by a "sealing record." If you find such a reference, there are ways to verify the existence of such a sealing.
Let me caution anyone who starts to investigate this practice from outside of documented, historical records. I cannot emphasize enough the amount of pure garbage in print and on the Internet about this subject. This is especially true now that there have been certain court rulings in Utah on the subject of polygamy. Sorting out the history from those who would attack the Church for their own gain or for other personal reasons is very difficult.