When the 8th guru died, rival 9th gurus disputed the succession. The true 9th guru, who fortunately defeated the false 9th guru, was magnanimous to his rival. We know he was the real 9th guru because he said he was and a guru wouldn’t lie about something like that. The false 9th guru never accepted the result of the transfer of guruship.
So it would be much better if the president of the USA named their successor well in advance.