All Buddhas are followers of Shakyamuni Buddha (no exceptions SGI)

"When Shakyamuni Buddha revealed that he had gained enlightenment in the far distant past, it became apparent that all the other Buddhas were emanations of Shakyamuni. When the Buddha preached the earlier sutras and the first half, or theoretical teaching, of the Lotus Sutra, the other Buddhas were pictured as standing on an equal footing with Shakyamuni, after completing their respective practices and disciplines. Therefore, the people who take one or another of these Buddhas as their object of devotion customarily look down onShakyamuni Buddha. But now it becomes apparent that Vairochana Buddha, who is described in the Flower Garland Sutra as being seated on a lotus pedestal, and the various Buddhas who appear in the sutras of the Correct and Equal and the Wisdom periods, such as the Mahāvairochana Sutra, are all in fact followers of Shakyamuni Buddha."