Hi,

If you inherit the "mail.thread" model for you specific model you will be able to activate the track visibility feature.

add this lines to your form view

<div class="oe_chatter">
    <field name="message_follower_ids" widget="mail_followers" groups="base.group_user"/>  
    field name="message_ids" widget="mail_thread"/> 
</div>

And for all field that you add the attribute track visibility, odoo will notify all users following an object when  that filed is changed.

fields.Char(track_visibility='onchange')

Best regards.