Information around contact odering in messenging for contact keys can be found below;

• Any contact linked against a student in Enrolments has the potential to be utilised as a communications contact in Messaging. Whether the contact/s belong to a household or not does not affect whether the contact will be available in Messaging.
• In Enrolments > Associated Contacts users are given the ability to add contacts against a student as well as order the contacts according to priority. The ordering will be important as it plays a part in determining whether the contact will be automatically selected as the 1st or subsequent communications contact. Contacts also will require the Receives Absences permission selected against them to be eligible for use in Messaging.
• Messaging > Student's Contacts
• In the Address Book the student's available contacts should be listed in the same ordering as configured in Enrolments