Buying Influence Controller

public with sharing class EditableBuyingInfluenceExtension extends EditableBuyingInfluenceList
{


 public Opportunity_Positioning__c mydemo {get; private set;}
 public List<Quota__c> children {get; set;}
  public EditableBuyingInfluenceListExtension(ApexPages.StandardController stdController) 
  {
    super(stdController);

this.mydemo = [SELECT Id,
                              Name, ( select id,name from  Buying_Influence__r)
                            FROM Opportunity_Positioning__c
                            WHERE Id =: stdController.getRecord().Id];
    
    this.childList = [SELECT Id,
                          Name,
                          SCOP__c,
                          Influencer_Name__c,
                          Buying_influence_role__c,
                          Degree_of_Influence__c,
                          Rating_for_base_covered__c,
                          Equivalent_Collinson_Stakeholder__c
                          Evidence_to_support_your_rating__c
                          
                      FROM Buying_Influence__c
                      WHERE Opportunity_Positioning__c =: mysObject.Id];

     children = new List<Buying_Influence__c>();
     children.addALL(this.childList);
  }

  /*
   * This method is necessary for reference on the Visualforce page, 
   * in order to reference non-standard fields.
   */
  /*public List<Quota__c> getChildren()
  {
    return (List<Quota__c>)childList;
  }*/

  public PageReference saveChildren(){

      try{
           upsert children;
           //use the redirect method like the demographic page if needed after upsert
      }catch(DMLException saveEx){
         //do something
       }

       return null;
   }


  public override sObject initChildRecord()
  {
    Buying_Influence__c child = new Buying_Influence__c();
    child.Opportunity_Positioning__c = mydemo.Id;
   
    
    return child;
  }
}

<apex:page standardcontroller="Opportunity_Positioning__c">
           extensions="EditableBuyingInfluenceExtension"
<apex:sectionheader title="{!$ObjectType.Buying_Influence__c.label} Edit" subtitle="{!IF(ISNULL(Buying_Influence__c.Name), 'New Buying Influence',Buying_Influence__c.Name)}"/>
    <apex:form >
        <apex:pageblock mode="edit" title="{!$ObjectType.Buying_Influence__c.label} Edit">
            <apex:pageblockbuttons >
                <apex:commandbutton value="Save" action="{!Save}"/>
                <apex:commandbutton value="Cancel" action="{!Cancel}"/>
            </apex:pageblockbuttons>
            <apex:pageblocksection title="Information" showheader="true" columns="2">
                    <apex:outputText> value="{!Opportunity_Positioning__c.Name}"/>
                    <apex:outputText> value="{!Opportunity_Positioning__c.Opportunity__c}"/>
                    <apex:pageblocksectionitem />
            <apex:pageBlockSectionItem >
                <apex:pageblocksection id="childList" columns="1" title="Buying Influence" collapsible="false">
                <apex:variable var="rowNum" value="{!ZERO}" />
                <apex:outputLabel value="No Buying Influence currently exist. Click below to Add." rendered="{!NOT(hasChildren)}"/>
                    <apex:pageBlockTable value="{!children}" var="Buying Influence" rendered="{!hasChildren}">
                    <apex:column headerValue= "Buying Influence">
                    <apex:inputfield value="{!Buying_Influence__c.Name}" required="true"/>
                    <apex:column headerValue= "SCOP">
                    <apex:inputfield value="{!Buying_Influence__c.SCOP__c}" required="true"/>
                    <apex:column headerValue= "Influencer Name">
                    <apex:inputfield value="{!Buying_Influence__c.Influencer_Name__c}" required="true"/>
                    <apex:column headerValue= "Buying Influence role">
                    <apex:inputfield value="{!Buying_Influence__c.Buying_influence_role__c}" required="true"/>
                    <apex:column headerValue= "Degree of Influence">
                    <apex:inputfield value="{!Buying_Influence__c.Degree_of_Influence__c}" required="true"/>
                    <apex:pageblocksectionitem />
               </apex:column>
               <apex:pageblocksection title="How well is based covered for this contact" showheader="true" columns="2">
               </apex:pageblocksection>
               </apex:column> headerValue="Rating for base covered">
                    <apex:inputfield value="{!Buying_Influence__c.Rating_for_base_covered__c}" required="true"/>
               </apex:column> headerValue="Equivalent Collinson Stakeholder">
                    <apex:inputfield value="{!Buying_Influence__c.Equivalent_Collinson_Stakeholder__c}" required="false"/>
               </apex:column> headerValue="Evidence to support your rating">
                    <apex:inputfield value="{!Buying_Influence__c.Evidence_to_support_your_rating__c}" required="false"/>
                    </apex:column>
                    <apex:column headerValue=" ">
                    <!-- This is the second half of the trick to keep track
                    of your row index for deletion. -->
                    <apex:variable var="rowNum" value="{!rowNum + 1}" />
                    <apex:commandLink value="Delete" action="{!removeFromList}" rerender="childList,messages" immediate="true"> 
     <apex:param name="removeIndex" assignTo="{!removeIndex}" value="{!rowNum}" />
            </apex:commandLink>
          </apex:column>
        </apex:pageBlockTable>
        <apex:commandButton value="Add Buying Influence" action="{!addToList}" rerender="childList, messages" immediate="true" />
      </apex:pageBlockSection>
     </apex:pageblocksectionitem>
     </apex:outputtext> </apex:outputtext>
    </apex:pageblocksection>
</apex:pageblock>
</apex:form>
</apex:page>