SES reversal after settlement should not allowed

Dear Experts,

our client have a scenario in PS where system allows users to reverse the SES after the settlement which causes wrongs no is AUC (negative values) and wrong commitments. Client wants the system wont allow SES reversal after partial/full settlement. Is there any way I can block or error when user try to do the SES reversal after settlement of that particular WBS? Please help me out on this scenario. Thanks in advance.