[DarkLored]

I would suggest making it from scratch because if you try to edit a gamemode you have no knowledge about it and you have to deal with all the problems that original developer has created, doing it from scratch puts less stress on you because you can organize the way you want it to be.

if you still want to edit the godfather script, refer to this link.
https://sampforum.blast.hk/showthread.php?tid=7797

Hope that answered your question and I hope you'll succeed with your goal.