How can I add List of objects in a conditional state in guided decision table?

Question

I am working on a Guided decision table in JBPM.
I have a requirement like I have 1 college object in that I have a Student and a Fee object.
I want to apply a condition on multiple Student objects by passing a JSON containing College object and multiple Student objects in that. An then want to apply a discount on Fee object as it contains multiple fee variable in it. Like

College{
String name;
String city;
Student student;
Fee fee;
}

Student{
 String name;
 int id;
 float fatherincome;
}

Fee{
int tutionFee;
float examFee;
}

So here I want to apply condition in a decision table that according to each student's father income concession on fee will be given. So I will pass Json of college like it:

Basically, this is JSON so I want to know that how can I achieve this thing in guided decision table. When I am making a condition in GDT then able to select only student and fee as normal fields from college Data object but I want to select fields from Student and Fee objects for my requirement so How can I select this. Please help me. Any suggestions or guidance will be appreciated.