Kang Cangzi mentioned "I am a teacher" in the first chapter of "The True Sutra of the Cave Spirit". His views are Taoist, so he must be a disciple of Lao Dan.
As for "who is the big disciple? Who is the second disciple? " . . . I have to admit that you have supplemented this question very well!
It seems that no one has studied this problem. . . . . . . . . .