Hello Jorge , 

If i understand your issue you don't want the notifications message to be send to the followers of the document you're sending , maybe this odoo context mixin will help you

• mail_create_nosubscribe: at create or message_post, do not subscribe the current user to the record thread
• tracking_disable: at create and write, perform no MailThread features (auto subscription, tracking, post, ..)

pass this context to your function using with_context (mail_create_nosubscribe=False,tracking_disable=False)

I hope this answer help you if not you can explain more your issue or add an excerpt from the code you have issue with.