I am showing a table that includes records from parent and child objects. I have something working OK, except that it repeats headings for the child records in each parent row.

Here is query:

CompChanges = [Select Name,(Select Maturity__r.Name,Total__c,ScheduleTracking__c,ExpenseTracking__c,
                                CapitalTracking__c,LateStart__c,Late__c
                                From dbPracticeChanges__r) From Competency__c];

Using the VF below the picture, I get child table headers in each parent row. I really want to have the child headers appear in the top of the table one time. How can I change the VF below the table to do that?  Any help much appreciated.

<apex:page controller="dbPracticeChangesController">
    <apex:form >
      <apex:pageblock >
         <apex:pageblocktable value="{!ChangeList}" var="cs">
          <apex:column headervalue="Competency">    
            <apex:outputtext value="{!cs.Name}"/>
          </apex:column>
            <apex:column >
                
                <apex:facet name="header">
                   Practice Status  
                </apex:facet>
                <apex:pageblocktable value="{!cs.dbPracticeChanges__r}" var="db">                   
                   <apex:column headervalue="Maturity">
                     <apex:outputtext value="{!db.Maturity__r.Name}"/>
                   </apex:column>
                   <apex:column headervalue="Total">
                      <apex:outputtext value="{!db.Total__c}"/>
                   </apex:column>
                   <apex:column headervalue="Schedule">
                      <apex:outputtext value="{!db.ScheduleTracking__c}"/>
                   </apex:column>
                   <apex:column headervalue="Expense">
                      <apex:outputtext value="{!db.ExpenseTracking__c}"/>
                   </apex:column>
                   <apex:column headervalue="Capital">
                      <apex:outputtext value="{!db.CapitalTracking__c}"/>
                   </apex:column>
                   <apex:column headervalue="Late Start">
                      <apex:outputtext value="{!db.LateStart__c}"/>
                   </apex:column>
                   <apex:column headervalue="Late">
                      <apex:outputtext value="{!db.Late__c}"/>
                   </apex:column>
               </apex:pageblocktable>
          </apex:column>
          

        </apex:pageblocktable>
       </apex:pageblock>
      </apex:form>
</apex:page>