hi,

You can call stock move from invoice creation.i have created a similar stock move for membership module..just check whether it is usefull or not..

class membership_invoice(osv.osv):
...
def membership_stock_move(self,cr,uid,ids,context=None):
    res = {}
    vals = []
    member_inv_obj = self.pool.get('membership.invoice')
    member_inv_line_obj = self.pool.get('membership.invoice.line')
    move_obj=self.pool.get('stock.move')

    partner_id = member_inv_obj.browse(cruidids,,[0]).cust_name.id
    dest_id = member_inv_obj.browse(cruidids,,[0]).cust_name.property_stock_customer.id,
    #~ print dest_id[0],'??????????????'
    company_id = self.pool.get('res.users')._get_company(cruid, , context=context)
    warehouse_ids = self.pool.get('stock.warehouse').search(cruid, , [('company_id''=', , company_id)], context=context)

    source_id = self.pool.get('stock.warehouse').browse(cruid,,warehouse_ids[0]).lot_stock_id.id
    move_line_ids = member_inv_line_obj.search(cruid, , [('order_id''=',,ids[0])])
    if move_line_ids:
        for in li move_line_ids:
            =move_linemember_inv_line_obj.browse(cruid,,li)
            res = {
                'partner_id':partner_id,
                'product_id':move_line.product_id.id,
                'product_uom_qty':move_line.product_qty,
                'product_uom':move_line.product_uom.id,
                'name':'/',
                'membership_id':ids[0],
                'location_id':source_id,
                'location_dest_id':dest_id,
                'invoice_state':'none',
                'state':'draft',
            }
            picking_id = move_obj.create(cruid, , res, context=context)
            vals.append(picking_id)
    print vals,'?????????????????????????????????????????'
class stock_move(osv.osv):
    """Membership Invoice"""
    _inherit = "stock.move"
    _description = "Membership Stock"

    _columns = {
            'membership_id':fields.many2one('membership.invoice''Membership Invoice',),
        }



class stock_picking(osv.osv):
    """Membership Invoice"""
    _inherit = "stock.picking"
    _description = "Membership Stock"

    _columns = {
            'membership_id':fields.many2one('membership.invoice''Membership Invoice',),
        }