There absolutely was a shady and questionable succession of Brigham Young. It caused several major permanent schisms within your church!
Does “RLDS” ring a bell? What about Sidney Rigdon’s “The Church of Jesus Christ”? James Strang?
I think it is a devastating blow to the LDS that Joseph Smith’s legal wife Emma didn’t even follow Brigham Young after Joseph’s death. She joined the RLDS with two of their sons. Why was a large part of Joseph Smith’s immediate family led astray?
Brigham Young seemed to have campaigned his way into the position. He changed the intended line of succession.
Certainly Brigham Young was A senior apostle, but not THE senior apostle. Sidney Rigdon was the remaining member of the First Presidency and OBVIOUSLY had seniority over Brigham Young as we all know.
This would be equivalent back in the day of Boyd K. Packer, the current (and prior to Hinckley’s death) President of the Quorum of the 12 becoming “prophet” before Thomas S. Monson. Monson was a member of the First Presidency AND more importantly, had seniority over Boyd K. Packer.
After Joseph’s death, Brigham Young actually proposed that the “Quorum of the Twelve be named the church’s leadership” (it wasn’t already “understood” as you stated). The church members then VOTED on whether or not to accept the Twelve as the new guardians over the church. The majority voted in favor of the Twelve to Brigham Young’s benefit.
Seriously, why would God allow his just-barely “one true” RESTORED church to be fractured like that?
Talk about an apostasy!