My problem is that when I make a Website Sale in Odoo V9, and check the order in Sales Order, the Warehouse is a Default Warehouse, not the one where the product is in. 

[Edit]  Found this class in sale_stock.py, so I must assume it's impossible to have have multiple warehouses in online shop without multicompany because every warehouse is set up with company id=1 ?

class SaleOrder(models.Model): 

 _inherit = "sale.order"
@api.model 

 def _default_warehouse_id(self): company = self.env.user.company_id.id 

 warehouse_ids = self.env['stock.warehouse'].search([('company_id', '=', company)], limit=1)                

 return warehouse_ids

Thank you for helping