what do you do when you come up with a separate song fragment that really feels like it should be in another (partially written) song [same subject matter, lyrical style etc] but you don't know how to insert it into the song? (bonus points if you know a way to change the tempo mid song to fit the separate fragment without it sounding bad)
i just file it as a different song. if when writing song 1 you spontaneously find song 2 automatically coming up, that's ok too, but i wouldn't demand it. especially if the tempos are different