Hi i created a module  with a model related to sale.order with a Many2one field. I added a notebook to the sale.order view with a tree view of my model, similar to order line.

http://pasteboard.co/r6AofgsQh.jpg

What i need to do is to prefill fields with current order (sale.order) and order date.

http://pasteboard.co/r6CcSwByC.jpg

my code:

Model

class waycon_rtv(models.Model):
    _description = 'Rtv' _name = 'waycon.rtv'
     #omitted fields that don't need to be prefilled
    order_id = fields.Many2one('sale.order', string='Order Reference', required=True, ondelete='cascade',
      index=True, copy=False) 

    date = fields.Date(string="Data", help="Data creazione documento", required=True)
 
    order_partner_id = fields.Many2one(related='order_id.partner_id', store=True, string='Customer')

#field added to sale.order
class waycon_custom_order(models.Model):
    _inherit = 'sale.order'
    rtv = fields.One2many( 'waycon.rtv', 'order_id',string='Related rtvs')

View:

<record id="my_view_sale_form_inherit" model="ir.ui.view">	
    <field name="name">view.sale.order.form.inherit</field>	
    <field name="model">sale.order</field>		
    <field name="type">form</field>	
    <field name="inherit_id" ref="sale.view_order_form"/>		
    <field name="arch" type="xml">			
 
         <notebook>		
         <page string="R.T.V." > 
         <field name="rtv" mode="tree,kanban" string="RTV"> 
             <tree String="RTV_tree"> 
                 <field name="date"/> 
                 <field name="amount"/> 
                 <field name="date"/> 
                 <field name="note"/> 
             </tree> 
         </field> 
         </page> 
         </notebook> 
  </field> 
</record>

The only field prefilled is partner.id and i still don't understand how odoo do it since it's relater to order_id that is not filled. I wasn't able to add images directly in post so i used pasteboard and copy/past links.

Thank You in advance