I added a one2many field by custom module like this : 

from openerp.osv import fields, orm

class AccountVoucher(orm.Model):

    _inherit = 'account.voucher'
    _name = 'account.voucher'
    _columns = {
        'bls_to_pay': fields.one2many('stock.picking.out','bl_id','BLS to pay'),
    }

Obviously I added on stock.picking.out (and stock.picking) a many2one field 'bl_id' like this : 

'bl_id': fields.many2one('account.voucher','Bls to pay'),

On the XML Side, I have my one2many field getting his values by an on change method, depending on the selected partner ( I made an onchange method on partner_id field ).

Now, when I select a partner, there are values displayed on the one2many field, I want to get the one2many fiel values, how this can be possible ?

I Know that a one2many field is a logical field, so data are stored on the stock.picking.out model, on the foreign key ( many2one ), I want to know how to access the one2many field values displayed via the foreign key many2one ?