You can send an instant message to large groups of people (everyone in a hierarchy) with the itslearning Mass Messaging feature. Mass Messaging can be opened from the Admin menu or directly from the messages Inbox. It's quick, easy and mobile friendly. 

You can also set the organization/school as the sender in Mass Messaging, to inform recipients that the message is coming from their organization. If you are sending to members of multiple schools, you can determine which school should be the 'sender'. 


See the video for more information on how to send mass messages to multiple users.