@GeorgeMTO I haven't read Vol 11 yet, so this guess may have already been proven wrong. But I think, in the original timeline, Momo was never freed from Bifrons. My best guess is, in the original timeline:
Abel and the Hero team meet Momo in the human farm, and Momo guides them to the castle
Momo gets captures, vampirized.
Abel et al. beat Bifrons, but the Heroes of Fire, Wood, and Iron die
Momo is "freed" because Bifrons is no longer around to command her
Cain invades Labyrinthos, the Hero of Ground, Johnnie's subordinates, and the ancient dragons aside from Mel die
The divergence point must have been before the team was even assembled, because in the new timeline the Hero of Iron already gave up on the fight and shouldn't have fought Bifrons at all, and maybe that was the difference that led to them being captured.
Also, after the fight against the resurrected Bifrons, the Grandsage mentions that she couldn't have fought against him since he sired her. I think the original timeline was intact to that point: Makoto hadn't met Momo in the past, hadn't severed the thread of fate, and so Grandsage Prime couldn't oppose resurrected Bifrons.