Partial code for adding a new predefined condition:
Dim Cls As Designer.Class
Dim PreCond As Designer.PredefinedCondition
Set Cls = Univ.Classes.FindClass("Class Name")
Set PreCond = Cls.PredefinedConditions.Add("Condition Name")
PreCond.Where = "SQL statement of the condition"
You can tweak this a bit to copy from another condition, effectively “duplicating” the object.
Take a look at the code in this utility … Copy Data Providers / Copy Report Variables. It includes examples for adding condition objects, and one option is for predefined conditions.