Adding XML logic

I've written an XML document that works as expected - but I'm trying to add situational logic to one of my fields. In the "SSN" field name, the goal of the logic would be to created an IF, THEN statement where IF SSN values = 000-00-0000, 111-11-1111, 222-22-2222, ... up to 999-99-9999 then covert those values to a null type or a blank insert.

Below is the code im working with an the first few lines of the map

<?xml version="1.0" encoding="utf-8" ?>
<ExportTemplate FileNewLine="RecordByRecord">
  <TemplateDataMapping>
    <DataSource NameInTemplate="Master" NameInDataSet="Master" PositionDataSet="1" />
  </TemplateDataMapping>

  
  <FileLayouts>
    <FileLayout Name="Detail" FieldCount="44" DataSource="Master" Position="1" Delimiter="\t" HasHeader="false" >
      <FieldMappings>
        <FieldMapping FieldName="FamilyIndex" DataField="FamilyIndex" Position="1" Width="15" />
        <FieldMapping FieldName="SSN" DataField="SSN" Position="2" Width="11"  />