Who is telling you about all this - Joseph Smith - therefore it is from smith's mouth.
President Brigham Young had this to say concerning the birth of Christ: "The man Joseph, the husband of Mary, did not, that we know of, have more than one wife, but Mary the wife of Joseph had another husband" (Deseret News, October 10, 1866).
Galatians 1:6-10 (King James Version)
6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
9 As we said before, so say I now again, if any man preach any other gospel unto you than that ye have received, let him be accursed.