Hello Mohamed,

To do this, on your button action you would need to copy all items from the "mail.message" model where the "res_id" = opportunity_id and the "model" = "crm.lead". Duplicate these and change the "res_id" to your new project id and "model" to "project.project".

This would look something like this:

# get all messages on crm record
all_messages_crm = self.env["mail.message"].search(["&", ("res_id", "=", original_crm_object.id), ("model", "=", "crm.lead")])

# copy these messages and change the res_id and model
for crm_message in all_messages_crm:
    crm_message.copy({"model": "project.project", "res_id": new_project_object.id})

This function should work, I have not tested but the theory should be there. 

I hope this helps!

Merry Christmas! 

i try to get all chatter but no success. pls let me know how did you do