diff --git a/addons/project/models/project_task.py b/addons/project/models/project_task.py
index 01360b31fdb..657a4158dca 100644
--- a/addons/project/models/project_task.py
+++ b/addons/project/models/project_task.py
@@ -190,7 +190,7 @@ class Task(models.Model):
     # In the domain of displayed_image_id, we couln't use attachment_ids because a one2many is represented as a list of commands so we used res_model & res_id
     displayed_image_id = fields.Many2one('ir.attachment', domain="[('res_model', '=', 'project.task'), ('res_id', '=', id), ('mimetype', 'ilike', 'image')]", string='Cover Image')
 
-    parent_id = fields.Many2one('project.task', string='Parent Task', index=True, domain="['!', ('id', 'child_of', id)]")
+    parent_id = fields.Many2one('project.task', string='Parent Task', index=True, domain="['!', ('id', 'child_of', id)]", tracking=True)
     child_ids = fields.One2many('project.task', 'parent_id', string="Sub-tasks", domain="[('recurring_task', '=', False)]")
     subtask_count = fields.Integer("Sub-task Count", compute='_compute_subtask_count')
     closed_subtask_count = fields.Integer("Closed Sub-tasks Count", compute='_compute_subtask_count')
@@ -1564,6 +1564,26 @@ class Task(models.Model):
         self.recurrence_id.task_ids.recurring_task = False
         self.recurrence_id.unlink()
 
+    def action_convert_to_subtask(self):
+        self.ensure_one()
+        if self.project_id:
+            return {
+                'name': _('Convert to Task/Sub-Task'),
+                'type': 'ir.actions.act_window',
+                'res_model': 'project.task',
+                'res_id': self.id,
+                'views': [(self.env.ref('project.project_task_convert_to_subtask_view_form', False).id, 'form')],
+                'target': 'new',
+            }
+        return {
+            'type': 'ir.actions.client',
+            'tag': 'display_notification',
+            'params': {
+                'type': 'danger',
+                'message': _('Private tasks cannot be converted into sub-tasks. Please set a project for the task to gain access to this feature.'),
+            }
+        }
+
     # ---------------------------------------------------
     # Rating business
     # ---------------------------------------------------
diff --git a/addons/project/views/project_task_views.xml b/addons/project/views/project_task_views.xml
index b61e3054db6..62131f10958 100644
--- a/addons/project/views/project_task_views.xml
+++ b/addons/project/views/project_task_views.xml
@@ -291,7 +291,20 @@
                         </button>
                         <button name="%(project_task_action_sub_task)d" type="action" class="oe_stat_button" icon="fa-tasks"
                             invisible="not id or subtask_count == 0" context="{'default_user_ids': user_ids, 'default_project_id': project_id, 'default_milestone_id': milestone_id}">
-                            <field name="subtask_count" widget="statinfo" string="Sub-tasks"/>
+                            <div class="o_field_widget o_stat_info">
+                                <div class="d-flex align-items-baseline gap-1">
+                                    <span class="o_stat_value order-1">
+                                        <field name="subtask_count" widget="statinfo" nolabel="1"/>
+                                    </span>
+                                    <span class="o_stat_text order-2">Sub-tasks</span>
+                                </div>
+                                <div class="d-flex align-items-baseline gap-1">
+                                    <span class="o_stat_value">
+                                        <field name="closed_subtask_count" widget="statinfo" nolabel="1"/>
+                                    </span>
+                                    <span class="o_stat_text order-2">Closed</span>
+                                </div>
+                            </div>
                         </button>
                         <button name="action_dependent_tasks" type="object" invisible="dependent_tasks_count == 0" class="oe_stat_button" icon="fa-tasks" groups="project.group_project_task_dependencies">
                             <field name="dependent_tasks_count" widget="statinfo" string="Blocking Tasks" />
@@ -506,6 +519,27 @@
             </field>
         </record>
 
+        <record id="project_task_convert_to_subtask_view_form" model="ir.ui.view">
+            <field name="name">project.task.convert.to.subtask.form</field>
+            <field name="model">project.task</field>
+            <field name="arch" type="xml">
+                <form>
+                    <div class="text-muted o_row mb-3">
+                        To transform a task into a sub-task, select a parent task. Alternatively, leave the parent task field blank to convert a sub-task into a standalone task.
+                    </div>
+                    <group>
+                        <field name="project_id" invisible="1" />
+                        <field name="company_id" invisible="1" />
+                        <field name="parent_id" domain="[('id', '!=', id)]" context="{'search_default_project_id': project_id, 'search_default_open_tasks': 1}" /> 
+                    </group>
+                    <footer>
+                        <button string="Convert Task" class="btn-primary" special="save" data-hotkey="q"/>
+                        <button string="Discard" class="btn-secondary" special="cancel" data-hotkey="z" />
+                    </footer>
+                </form>
+            </field>
+        </record>
+
         <record model="ir.ui.view" id="view_task_kanban">
             <field name="name">project.task.kanban</field>
             <field name="model">project.task</field>
@@ -981,6 +1015,17 @@
             </field>
         </record>
 
+        <record id="action_server_convert_to_subtask" model="ir.actions.server">
+            <field name="name">Convert to Task/Sub-Task</field>
+            <field name="model_id" ref="project.model_project_task"/>
+            <field name="binding_model_id" ref="project.model_project_task"/>
+            <field name="binding_view_types">form</field>
+            <field name="state">code</field>
+            <field name="code">
+                action = record.action_convert_to_subtask()
+            </field>
+        </record>
+
         <record id="project_task_action_from_partner" model="ir.actions.act_window">
             <field name="name">Tasks</field>
             <field name="res_model">project.task</field>