Does anyone who knows how to set parent_id while creating it's child on onchange method? The case is this, i have my class installment and installment_schedule. These are some of its definition:

    class installment(orm.Model):
        _name = 'installment' 
        _columns = { 
                    'date_start' : fields.date('Date Start'), 
                    'date_end' : fields.date('Date End'), 
                    'factor' : fields.function(_get_factor,.....), 
                    'child_ids': fields.one2many('installment.schedule','parent_id','Schedule'),
                   } 
                    
       def on_change_fields(self, cr, uid, ids, d_start, d_end, factor, context=None): 
           i = seq = 0 
           range = 24 
           sched_obj = self.pool.get('installment.schedule') 
           while seq < range:
                 while i < factor:
                     date = datetime.strptime(date_start, '%Y-%m-%d') + relativedelta(months=+i) 
                     sched_obj.create(cr,uid,{ 
                                              "regular_date" : date.strftime('%Y-%m-%d'),
                                              "seq" : seq, 
                                             }  
                 i += 1 
           seq += 1 
       return True

    ... 
    installment() 

    class installment_schedule(orm.Model): 
        ...
        _columns = { 
                   'parent_id' : fields.many2one('installment','Installment'),
                   'regular_date' : fields.date('Regular Date'), 
                   'seq' : fields.integer('Sequence'), 
        }
       ...
    installment_schedule()

What i want is whenever that three fields (in installment class) are being change i also want to populate the installment_schedule class and at the same time show it on my installement_view.xml.

Any help/suggestion/recommendation is highly appreciated