Try this:
- alias: notify on zone enter/leave
trigger:
- platform: zone
entity_id:
- person.brayden
- person.jordyn
zone: zone.centennial
event: enter
- platform: zone
entity_id:
- person.brayden
- person.jordyn
zone: zone.centennial
event: leave
action:
- variables:
event: "{{ 'left' if trigger.event == 'leave' else 'arrived at' }}"
person: "{{ trigger.to_state.attributes.friendly_name }}"
zone: "{{ trigger.zone.attributes.friendly_name }}"
- service: notify.mobile_app_craigs_s20_mobile_app
data:
message: >
{{ person + ' ' + event ' ' + zone }}
- service: notify.mobile_app_richelles_s10_mobile_app
data:
message: >
{{ person + ' ' + event ' ' + zone }}
You just need to add an enter and leave trigger for each zone. Unfortunately you can’t have one trigger for multiple zones or for leave and enter event.
Edit:
And please format your code correctly. Read the community guidelines here, point 11.