Tutorial video on how to send to a selection list in PowerSchool such as HAL Participants (permission restricted): https://drive.google.com/file/d/1r_DEwgK5baIYQKOkhAJphxnDImWD_7kl/view

In PowerSchool as DISTRICT, use this search string in the PowerSchool student search to create the selection list of students:  Grade_Level in 4,5,6,7,8;NE_HALParticipate=1


You will get the list of students then on the left side of PowerSchool, click "Message Sender" to start School Messenger with the parents/contacts as the number of students in your selection list already set as the recipients.  Now just add yourself to the recipients list, create, and send the message.