Employee Company Credit Card charges, expense reports, client billables

Our small business is fairly new to NS.  I have a use case that I am not sure how to solve/tackle.  Here is the situation:

1.  Employees travel and rate a standard per diem for meals and incidental expenses.
2.  Employees have a corporate credit card for travel expenses.
3.  Per diem and transportation are billable to the client on the contract.
4.  I import credit card data from the corporate credit card.

We are trying use the expense reports in NS and I wanted to have employees list per diem as an expense and then list credit card charges as company paid and totalled into the "Advance to Apply" field or perhaps a new "Company Paid" field; the total on the report would show their rated per diem remainder or what they owe the company if they overspent.