odoo-event-addons/event_question_sale/views/event_event.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

  <record id="event_event_view_form_inherit" model="ir.ui.view">
    <field name="name">event.event.view.form.inherit</field>
    <field name="model">event.event</field>
    <field name="inherit_id" ref="website_event_questions.event_event_view_form" />
    <field name="arch" type="xml">
      <xpath expr="//field[@name='once_per_order']/.." position="attributes">
        <attribute name="class">o_label_nowrap</attribute>
      </xpath>
      <field name="once_per_order" position="after">
        <field name="add_products" />
        <field name="qty_by_attendees" />
      </field>
      <xpath expr="//field[@name='question_ids']/form//tree" position="attributes">
        <attribute name="editable">0</attribute>
      </xpath>
      <xpath expr="//field[@name='question_ids']/form//tree" position="inside">
        <field name="extra_product_ids" widget="one2many" options="{'no_quick_create': 1}"
          attrs="{'cdolumn_invisible':[('parent.add_products','!=',True)]}">
          <!-- <form>
            <group>
              <group>
                <field name="product_id" />
                <field name="price_unit" />
              </group>
              <group>
                <field name="quantity" />
                <field name="uom_id" />
                <field name="uom_category_id" invisible="1" />
              </group>
            </group>
          </form> -->
          <tree editable="bottom">
            <field name="product_id" />
            <field name="price_unit" />
            <field name="quantity" />
            <field name="uom_id" />
            <field name="uom_category_id" invisible="1" />
          </tree>
        </field>
      </xpath>
    </field>
  </record>

</odoo>