According to Andrea Trincia asked me to show her how to add invoice id to refund I will show my solution here that of course could have been done better. This just solved my issue I got on that point.

I made an addon with that account_invoice.py file:

# -*- coding: utf-8 -*-
from openerp.osv import fields, osv

class account_invoice(osv.osv):
    _name= 'account.invoice'
    _inherit= 'account.invoice'

    def refund(self, cr, uid, ids, date=None, period_id=None, description=None, journal_id=None, context=None):
        invoice_obj = self.pool.get('account.invoice')

        new_ids = super(account_invoice, self).refund(cr, uid, ids, date, period_id, description, journal_id, context)

        for refund_id ,invoice in zip(new_ids, self.browse(cr, uid, ids)):
            self.write(cr, uid, refund_id, {'origin': invoice.internal_number})

        return new_ids

account_invoice()

This just adds the id of invoice to origin field. There might have been a one2one connection between but that has not been necessary for my issue.