Any ways to creating Custom Challenges for addon packs?

[NTVAMGames]

Is there any way to make custom (optional) unlockable challenges for Ring Racers addons? I want to do one for an upcoming multi-character pack that I'm working on, but nobody else did custom challenges for their character pack mods.

 

[Red Guy]

Not a character pack but there are custom challenges in the CTR track pack. You can maybe ask them how they implemented the secret maps since unlockable characters though custom challenges could be made in a similar way