Coworking/coworking_relation/views/coworker_views.xml

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

<odoo>

<!-- Form -->
  <record id="view_form_coworker" model="ir.ui.view">
    <field name="name">Coworker Form adaptations</field>
    <field name="model">coworking.coworker</field>
    <field name="inherit_id" ref ="coworking_coworker.view_form_coworker" />
    <field name="arch" type="xml">
      <notebook position="inside">
        <page string="Relation" name="Relation">
          <group name="relation">
            <field name="coworker_relation_ids" context="{'default_relation_id': active_id}" />
          </group>
        </page>
      </notebook>
    </field>
  </record>

</odoo>