diff --git a/mail_activity_team/models/mail_activity.py b/mail_activity_team/models/mail_activity.py
index 51cf198..46dd6de 100644
--- a/mail_activity_team/models/mail_activity.py
+++ b/mail_activity_team/models/mail_activity.py
@@ -1,34 +1,66 @@
 # Copyright 2018 Eficent Business and IT Consulting Services, S.L.
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
-from odoo import api, models, fields
+from odoo import api, models, fields, _
+from odoo.exceptions import ValidationError
 
 
 class MailActivity(models.Model):
     _inherit = "mail.activity"
 
-    def _get_default_team_id(self):
-        res_model = self.env.context.get('default_res_model', False)
-        model = self.env['ir.model'].search([('model', '=', res_model)],
-                                            limit=1)
-        domain = [('member_ids', 'in', [self.env.uid])]
+    def _get_default_team_id(self, user_id=None):
+        if not user_id:
+            user_id = self.env.uid
+        res_model = self.env.context.get('default_res_model')
+        model = self.env['ir.model'].search(
+            [('model', '=', res_model)], limit=1)
+        domain = [('member_ids', 'in', [user_id])]
         if res_model:
             domain.extend(['|', ('res_model_ids', '=', False),
                            ('res_model_ids', 'in', model.ids)])
         return self.env['mail.activity.team'].search(domain, limit=1)
 
-    team_id = fields.Many2one('mail.activity.team',
-                              default=lambda s: s._get_default_team_id(),)
+    team_id = fields.Many2one(
+        comodel_name='mail.activity.team',
+        default=lambda s: s._get_default_team_id(),
+    )
 
-    @api.onchange('res_model_id', 'user_id')
-    def _onchange_model_user(self):
+    @api.onchange('user_id')
+    def _onchange_user_id(self):
         res = {'domain': {'team_id': []}}
-        if self.team_id:
-            if self.user_id not in self.team_id.member_ids:
-                self.team_id = False
-        if self.res_model_id:
-            res['domain']['team_id'] = [
-                ('res_model_ids', 'in', self.res_model_id.ids)]
-        if self.user_id:
-            res['domain']['team_id'] = [
-                ('member_ids', 'in', self.user_id.ids)]
+        if not self.user_id:
+            return res
+        res['domain']['team_id'] = [
+            '|',
+            ('res_model_ids', '=', False),
+            ('res_model_ids', 'in', self.res_model_id.ids)]
+        if self.team_id and self.user_id in self.team_id.member_ids:
+            return res
+        self.team_id = self.with_context(
+            default_res_model=self.res_model_id.id).\
+            _get_default_team_id(user_id=self.user_id.id)
         return res
+
+    @api.onchange('team_id')
+    def _onchange_team_id(self):
+        res = {'domain': {'user_id': []}}
+        if not self.team_id:
+            return res
+        res['domain']['user_id'] = [('id', 'in', self.team_id.member_ids.ids)]
+        if self.user_id and self.user_id in self.team_id.member_ids:
+            return res
+        if self.team_id.user_id:
+            self.user_id = self.team_id.user_id
+        elif self.env.user in self.team_id.member_ids.ids:
+            self.user_id = self.env.user
+        else:
+            self.user_id = self.env['res.users']
+        return res
+
+    @api.multi
+    @api.constrains('team_id', 'user_id')
+    def _check_team_and_user(self):
+        for activity in self:
+            if activity.team_id and activity.user_id and \
+                    activity.user_id not in self.team_id.member_ids:
+                raise ValidationError(
+                    _('The assigned user is not member of the team.'))
diff --git a/mail_activity_team/models/mail_activity_team.py b/mail_activity_team/models/mail_activity_team.py
index 81d0676..f97c185 100644
--- a/mail_activity_team/models/mail_activity_team.py
+++ b/mail_activity_team/models/mail_activity_team.py
@@ -1,14 +1,71 @@
 # Copyright 2018 Eficent Business and IT Consulting Services, S.L.
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class MailActivityTeam(models.Model):
     _name = "mail.activity.team"
     _description = 'Mail Activity Team'
 
-    name = fields.Char(string='Name', required=True, translate=True)
-    active = fields.Boolean(string='Active', default=True)
-    res_model_ids = fields.Many2many('ir.model', string='Used models')
-    member_ids = fields.Many2many('res.users', 'mail_activity_team_users_rel',
-                                  string="Team Members")
+    @api.depends('res_model_ids', 'member_ids')
+    def _compute_missing_activities(self):
+        activity_model = self.env['mail.activity']
+        for team in self:
+            domain = [('team_id', '=', False)]
+            if team.member_ids:
+                domain.append(('user_id', 'in', team.member_ids.ids))
+            if team.res_model_ids:
+                domain.append(('res_model_id', 'in', team.res_model_ids.ids))
+            team.count_missing_activities = activity_model.search(
+                domain, count=True)
+
+    name = fields.Char(
+        string='Name',
+        required=True,
+        translate=True,
+    )
+    active = fields.Boolean(
+        string='Active',
+        default=True,
+    )
+    res_model_ids = fields.Many2many(
+        comodel_name='ir.model',
+        string='Used models',
+        domain=lambda self: [
+            ('model', 'in',
+             [k for k in self.env.registry if issubclass(
+                 type(self.env[k]), type(self.env['mail.activity.mixin']))
+              and self.env[k]._auto])
+        ],
+    )
+    member_ids = fields.Many2many(
+        comodel_name='res.users',
+        relation='mail_activity_team_users_rel',
+        string="Team Members",
+    )
+    user_id = fields.Many2one(
+        comodel_name='res.users',
+        string='Team Leader',
+        domain="[('id', 'in', member_ids)]",
+    )
+    count_missing_activities = fields.Integer(
+        string="Missing Activities",
+        compute='_compute_missing_activities',
+        default=0,
+    )
+
+    @api.onchange('member_ids')
+    def _onchange_member_ids(self):
+        if self.user_id and self.user_id not in self.member_ids:
+            self.user_id = False
+
+    def assign_team_to_unassigned_activities(self):
+        activity_model = self.env['mail.activity']
+        for team in self:
+            domain = [('team_id', '=', False)]
+            if team.member_ids:
+                domain.append(('user_id', 'in', team.member_ids.ids))
+            if team.res_model_ids:
+                domain.append(('res_model_id', 'in', team.res_model_ids.ids))
+            missing_activities = activity_model.search(domain)
+            missing_activities.write({'team_id': team.id})
diff --git a/mail_activity_team/models/res_users.py b/mail_activity_team/models/res_users.py
index b55ae84..e1f9cc3 100644
--- a/mail_activity_team/models/res_users.py
+++ b/mail_activity_team/models/res_users.py
@@ -6,6 +6,8 @@ from odoo import models, fields
 class ResUsers(models.Model):
     _inherit = "res.users"
 
-    activity_team_ids = fields.Many2many('mail.activity.team',
-                                         'mail_activity_team_users_rel',
-                                         string="Activity Teams")
+    activity_team_ids = fields.Many2many(
+        comodel_name='mail.activity.team',
+        relation='mail_activity_team_users_rel',
+        string="Activity Teams",
+    )
diff --git a/mail_activity_team/security/ir.model.access.csv b/mail_activity_team/security/ir.model.access.csv
index c5efccf..0a9918d 100644
--- a/mail_activity_team/security/ir.model.access.csv
+++ b/mail_activity_team/security/ir.model.access.csv
@@ -1,4 +1,4 @@
 "id","name","model_id:id","group_id:id","perm_read","perm_write","perm_create","perm_unlink"
 access_mail_activity_team_all,mail.activity.team.all,model_mail_activity_team,,1,0,0,0
 access_mail_activity_team_user,mail.activity.team.user,model_mail_activity_team,base.group_user,1,1,0,0
-access_mail_activity_team_system_user,mail.activity.team.system.user,model_mail_activity_team,base.group_system_user,1,1,1,1
+access_mail_activity_team_system_user,mail.activity.team.system.user,model_mail_activity_team,base.group_system,1,1,1,1
diff --git a/mail_activity_team/security/mail_activity_team_security.xml b/mail_activity_team/security/mail_activity_team_security.xml
index 9ac6363..e19398a 100644
--- a/mail_activity_team/security/mail_activity_team_security.xml
+++ b/mail_activity_team/security/mail_activity_team_security.xml
@@ -4,10 +4,10 @@
     <record id="mail_activity_rule_my_team" model="ir.rule">
         <field name="name">mail.activity: user: my team</field>
         <field name="model_id" ref="mail.model_mail_activity"/>
-        <field name="domain_force">['|', '&amp;'('team_id', '=', False),('user_id', '=', user.id),('team_id', '=', user.team_ids.ids)]</field>
+        <field name="domain_force">["|", ('team_id', 'in', user.activity_team_ids.ids), "&amp;", ('team_id', '=', False), ('user_id', '=', user.id)]</field>
         <field name="groups" eval="[(4, ref('base.group_user'))]"/>
         <field name="perm_create" eval="True"/>
-        <field name="perm_read" eval="True"/>
+        <field name="perm_read" eval="False"/>
         <field name="perm_write" eval="True"/>
         <field name="perm_unlink" eval="True"/>
     </record>
diff --git a/mail_activity_team/views/mail_activity_team_views.xml b/mail_activity_team/views/mail_activity_team_views.xml
index 52203d2..72b49a1 100644
--- a/mail_activity_team/views/mail_activity_team_views.xml
+++ b/mail_activity_team/views/mail_activity_team_views.xml
@@ -4,26 +4,34 @@
     VIEWS
 -->
 
-
     <!-- FORM VIEW -->
     <record id="mail_activity_team_view_form" model="ir.ui.view">
         <field name="name">mail.activity.team.view.form</field>
         <field name="model">mail.activity.team</field>
         <field name="arch" type="xml">
             <form string="Activity Team">
+                <header>
+                    <field name="count_missing_activities" invisible="1"/>
+                    <button name="assign_team_to_unassigned_activities" string="Assign to missing activities"
+                            type="object" class="oe_highlight"
+                            groups="base.group_no_one"
+                            attrs="{'invisible': [('count_missing_activities', '=', 0)]}"/>
+                </header>
                 <sheet string="Activity Team">
                     <div class="oe_button_box" name="button_box">
                         <button name="toggle_active" type="object"
-                            class="oe_stat_button" icon="fa-archive">
+                                class="oe_stat_button" icon="fa-archive">
                         <field name="active" widget="boolean_button"
-                            options='{"terminology": "archive"}'/></button>
+                               options='{"terminology": "archive"}'/></button>
                     </div>
                     <group>
                         <group name="base">
                             <field name="name"/>
+                            <field name="user_id" attrs="{'invisible': [('member_ids', '=', [])]}"/>
                         </group>
                         <group name="models">
-                            <field name="res_model_ids" widget="many2many_tags"/>
+                            <field name="res_model_ids" widget="many2many_tags"
+                                   options="{'no_create': True, 'no_open': True}"/>
                         </group>
                     </group>
                     <notebook>