JS Didn't Follow Old Testament Rules for the Old Testament Polygamy "Law"

If Jesus Christ came to fulfill the law of the Old Testament, why was Joseph Smith restoring polygamy and claiming it was an Old Testament law?

If Joseph Smith was simply restoring polygamy because it was an Old Testament law that had to be part of the "restoration of all things," why did Joseph Smith not follow the rules for polygamy given in the Old Testament? 

Leviticus 18 states there shall be no marriages to a pair of sisters or a mother/daughter pair simultaneously, yet Joseph married one mother/daughter pair, and three pairs of sisters.

Leviticus says:

 17 Thou shalt not uncover the nakedness of a woman and her daughter, neither shalt thou take her son’s daughter, or her daughter’s daughter, to uncover her nakedness; forthey are her near kinswomen: it is wickedness.

 18 Neither shalt thou take a wife to her sister, to vex her,to uncover her nakedness, beside the other in her life time.

In addition, both Exodus and Leviticus say that one should not covet or lie with thy neighbor's wife.

Exodus 20:17

 17 Thou shalt not covet thy neighbour’s house, thou shalt not covet thy neighbour’s wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing thatis thy neighbour’s.

Leviticus 18:20

 20 Moreover thou shalt not lie carnally with thy neighbour’s wife, to defile thyself with her.

Yet Joseph Smith practiced polyandry, meaning that he married women who were already married to and living with another living husband. He entered into at least 11 polyandrous marriages, and these marriages are acknowledged by the Church in the new essays on lds.org (). 

Bryan Hales argues that he never slept with any of his polyandrous wives, but there are credible sources to indicate that he did. If I have time I will provide links, but you can find this information in In Sacred Loneliness by Todd Compton. 

Strangely enough, Joseph Smith actually did both at the same time:

• He was married to a pair of sisters simultaneously who were both married to other men first at the time: Zina Huntington and Presendia Huntington.
• He was married to Patty Bartlett Sessions (mother) and Sylvia Sessions (her daughter) at the same time, and they both had living first husbands.

This is a graphic showing the relationships between the women he married:

Links:

• Graphic:
  http://www.mormoninfographics.com/2012/09/the-many-wives-of-joseph-smith.html

Official Church links:

• Church's new essay that concedes that Joseph Smith practiced polyandry, and that he was married to a large number of wives. The sister pairs are well-documented elsewhere in Church history and faithful members' original journals and documents.
  https://www.lds.org/topics/plural-marriage-in-kirtland-and-nauvoo?lang=eng
• Leviticus 18:17-18
  https://www.lds.org/scriptures/ot/lev/18.17-18?lang=eng#16
• Leviticus 18:20 regarding not sleeping with your neighbor's wife:
  https://www.lds.org/scriptures/ot/lev/18.20?lang=eng#16
• Exodus 20:17
  https://www.lds.org/scriptures/ot/ex/20.17?lang=eng#16

Apologetic sources:

• In Sacred Loneliness by Todd Compton. His book is cited in footnote 29 on the Church's official new essay about Plural Marriage in Kirtland and Nauvoo, so it cannot be considered an anti-Mormon source.