If you have un-invoiced or unpaid balances from your old timekeeping system, you may enter those balances in CaseFox just like other timekeeping items (e.g., time/expenses).  After creating clients and cases to mirror your old system, Add Note (Time/Expense Log) in each case individually in which a balance is due and enter that balance due amount.  This entry may be either a time or an expense entry.  The "service performed" may be "Previous due....".  Make sure to check "Show On Invoice" checkbox.  This amount will then automatically included in the next invoice that is generated for the case in CaseFox.