Oracle Trade Management Settlement - Chargeback

We are seeking a way to create an approval rule for Chargebacks only.  As of now we are only able modify in the approval rules claims/deductions at a high-level using dollar values.  We are trying to exclude chargebacks from our approval rule.  We only need credits to be reviewed and flow through a different approver based on dollar amounts.  How do I create an exception or rule for chargebacks only to be excluded?