Education Reimbursement Request and Validation

I need to know which module and function to setup Education Reimbursement request with validation as below, I have seen ICP but not covering the validation:

I have set up a payroll element which will be used to reimburse a worker children in the plan. I have to make sure for a given worker child should not allow more than education entitlement (based on worker grade and child age), So I will be able to Reimburse for approved request but limit them to education entitlement for each child.

Assume that worker (Peter and his child John aged 8 years entitlement should be worker entitlement based on grade and child age if child age is 8 years, then worker will get 80% of worker entitlement ($8500 * .8) = 6800