iExpense - Per Diem

Hello

We have a requirement for Per Diem:

For example, we have the following limits on the PerDiem

Breakfast      12.00
Lunch           15.00
Dinner           25.00
Total         $52.00

We have a requirement that if the user claims all 3 Meals, then the maximum reimbursement should be $42.
I can set the Daily maximum 42.00 to achieve this.
However if User picks a Meal Deduction, it should use the Total amount (i.e $52 - Deductions)
E.g If Deduction is for Breakfast, Reimbursable amount should be $52 - $12  ==== $40. But if I set the Daily maximum to $42, then the system calculates to $42 - $12 === $30...

Is it possible to do this ?

Thanks
Len