I mean it most likely did, yet serge remembers it but it never happened. so could it have happend in one demension is what I'm really asking. I mean I look at it like this.
1. Serge goes to the beach to meet leena then he goes to cape howl for something
2. Karsh attack and kid saves
3. He goes to termina with kid to help her
4. they find a way to the viper manor
5. go to water dragon isle to get ice breath (someone drops off the remedy for kid)
6. go to ft. dragoonia
7. they switch bodies
8. leave temporal distortion
9. get the star fragment from starky's space ship
10. get the fiddler crab
11. but now the dragons confront serge and tell him how to break the masamune's seal
12. get the einlanzer
13. break it but still can't enter need dragon relics
14. all the dragon lose to serge
15. steena takes him back to ft. dragoonia
16. the dragons give himk another dragon tear if they agree to kill FATE
17. use the dragon tear
18. go to chronopolise
19. harle sacrifices herself
20. frozen flame is stolen
21. kill FATE
22. Terra Tower rises
23. dragon god dies
24. terra tower falls
25.(this can vary if there is a timeline for the darkness beyond time then they free schala[this also determins wether or not the chrono cross will need to be made] if not i dont see the point in fighting him, maybe that is some thing that will allow chrono to kill lavos so that serge can live)