PHP Mysql广播消息系统

I'm trying to build a messaging system. The system that I create is only able to send message to a user. Trying to make a broadcast system and now I could send to multiple users. But now the problem is how I could make a notification when it's a new broadcast message, and how I could delete the broadcast message?

NB : When I delete the broadcast message with a user(example the user I use is 'user1'), the broadcast message will also deleted in another user account.

Can anybody help me how to solve this problem please?

EDIT

Here I got some table in my database

Table Message

id_message (INT(11))
to (VARCHAR(50))
from (INT(11))
title (TEXT)
user1delete (TINYINT(4))
user2delete (TINYINT(4))

Table Detail_Message

id_message (INT(11))
id_reply (INT(11))
from (INT(11))
message (TEXT)
user1read (TINYINT(4))
user2read (TINYINT(4))

Table Broadcast_Delete_Status

id_message (INT(11))
user (INT(11))

when the message is pointed to single user, the column 'to' in table message save the id of the recipient, and when it is a multiple or broadcast message, the column save "all user" or "all operator".