Hi Mario,

You have to code a custom module for it, that will  be better. By activating the developer mode you just can manipulate the view only by clicking the edit form view .  You can define the new fields from the following,

Settings -> Technical -> Database structure -> Models,

here you can add new fields in the corresponding model and also you can create a new model.

So to create a notebook and to have a tree view like this, you have to create a one2many relation field in the res.partner model and have to define the new model. I will add attach a sample code, hope it can give you an idea.

Thank You

<page string="Tour Programme">
       <field name="connect_tour_programme">
           <tree editable="bottom">
               <field name="no_of_days"/>
               <field name="tour_description"/>
               <field name="tour_breakfast"/>
               <field name="tour_lunch"/>
               <field name="tour_dinner"/>
           </tree>
       </field>

</page>

class TourBooking(models.Model):
    _name = 'tour.booking'
    _inherit = ['mail.thread', 'ir.needaction_mixin']
    
    connect_tour_programme = fields.One2many('tour.programme.new', 'tour_programme_connect', string='Tour Programme')

class TourProgrammeNew(models.Model):
    _name = 'tour.programme.new'

    tour_programme_connect = fields.Many2one('tour.booking', string="Connect")
    no_of_days = fields.Char(string='Days')
    tour_description = fields.Text(string='Description')
    tour_breakfast = fields.Boolean(string='Break Fast')