title: How to copy value of a module in another module [ODOO]
body: <p>I made a custom subscription module</p>
  
  <p>subscription.py</p>
  
  <pre><code>from openerp.osv import fields, osv
  
  class subscriptions(osv.osv):
      _name = "subscriptions.sub"
      _description = "subscriptions"
  
      _columns = {
          'sub_id': fields.integer('Subscription ID', size=10),
          'cust_id': fields.many2one('res.partner','customer_id', 'Customer ID')
       }
  </code></pre>
  
  <p>partner.py</p>
  
  <pre><code>from openerp import fields, models
  
  class Partner(models.Model):
      _inherit = 'res.partner'
  
      customer_id = fields.Integer('Customer ID'),
      subscription_id =  fields.One2many('subscriptions.sub', 'sub_id', 'Subscription ID')
  </code></pre>
  
  <p>When I create subscriptions from my customer module it also shows in the subscription module, but when I create a subscription in my subscription module it doesn't show in the customer module.</p>
  
  <p>Could I get some help in the right direction?</p>