Model_v2.php

<?php

class EducationDetail extends Model{

  fatherEducationLevel{
    return $this->belongsToOne('EducationLevel');
  }

  motherEducationLevel{
    return $this->belongsToOne('EducationLevel');
  }

  sisterEducationLevel{
    return $this->belongsToOne('EducationLevel');
  }
}

class FatherEducationLevel extends Model{
  
  public $table = 'education_levels';
  
  // 
  public function educationDetails(){
    return $this->hasMany('EducationLevel');
}

class MotherEducationLevel extends Model{
  
  public $table = 'education_levels';
  
  // 
  public function educationDetails(){
    return $this->hasMany('EducationLevel');
}

class SisterEducationLevel extends Model{
  
  public $table = 'education_levels';
  
  // 
  public function educationDetails(){
    return $this->hasMany('EducationLevel');
}