//controller to create parent child records record
 public class mainClass{

    List<Account> lstAccount{get;set;}
    List<FirstChild__c> lstfirstChild{get;set;}
    List<SecondChild__c> lstSecondChild{get;set;}
    List<ThirdChild__c> lstThirdChild{get;set;}

    public void createparent(){
        parentcontroller parent=new parentcontroller();
        lstAccount=parent.createParentRecords(); //this method will call the parentcontroller and there itself it will create parent record and return the created parent records
    }

    public void createFirstChil(){
        firstChildcontroller first=new firstChildcontroller();
        lstfirstChild=first.createFirstChildRecord(lstAccount); // This method will create first child records
    }

    public void createFirstChil(){
        secondChildcontroller first=new secondChildcontroller();
        lstSecondChild=first.createSecondChildRecord(lstAccount);// This method will create first child records
    }
    public void createFirstChil(){
        thirdchildcontroller first=new thirdchildcontroller();
        lstThirdChild=first.createThirdChildRecord(lstAccount);// This method will create first child records
    }

}