Changing Stories of Who’s in Charge
D&C 90:6; “And again, verily I say unto thy brethren, Sidney Rigdon and Frederick G. Williams, their sins are forgiven them also, and they are accounted as equal with thee in holding the keys of this last kingdom.”
D&C 43:3-6; “And this ye shall know assuredly—that there is none other appointed unto you to receive commandments and revelations until he be taken, if he abide in me.4 But verily, verily, I say unto you, that none else shall be appointed unto this gift except it be through him; for if it be taken from him he shall not have power except to appoint another in his stead. 5 And this shall be a law unto you, that ye receive not the teachings of any that shall come before you as revelations or commandments; 6 And this I give unto you that you may not be deceived, that you may know they are not of me.”
Revelations given in Kirtland, OH in February 1831 and March 8, 1833 respectively. See History of the Church 1:154-156 & 1:329-31.
As you can see this set of prophecies are intertwined as are most of the other stories Smith found himself making up along the way.
The prophecy from 90:6 was geared toward the three men involved, but about 14 months later Smith prophesied again that David Whitmer would be his successor and then several months after that (Dec. 1834) he changed his mind again and put Oliver Cowdery in charge for his succession.