I do have Iban's new City RP mod and RP Core. Although I don't know how to modify both of them so I'm stuck with this crappy City RP that doesn't have an AddFunds or other jobs.
Do not modify RP Core! It would only raise problems and issues that could make it not working at all. I saw a server that had modified it, and it was a failure. The data that was saved was nulled and invalid. Make an another add-on that works against RP Core. Kalphiter's Hourly Bell works against RP Time. You could see how he's doing.
I don't know how to modify both of them.
I really, really have no clue why everyone hates city RP. Yes, when you have a stuff for brains host, it can really suck. But otherwise, I had always enjoyed it better than freebuild.
Diggy's server is one of the best. He removed the worst parts, and added the best ones. But he didn't do it alone. He got help from several people.
THAT'S BECAUSE DIGGY ISN'T A handicap LIKE OTHERS
If anyone would take their time doing a bigger mod for RP Content, I would like to help him/her out by telling how to do it right.
Like?