I think the creation song, Ainulindalë, s for all this. Eru showed the Ainur his grand plan and essentially had them create the music to fulfill his vision. He allowed them room to do add their own ideas, but it had to harmonize with his intent. Even Melkor's discord was meant to be part of the fabric of the universe. The idea that Eru, or his agents, the Valar, nudge or outright push events and or people theoretically all relates back to the unfolding of that music.