Add alert groups
It would be helpful to create "alert groups" that consist of one or more SMS numbers, Slack channels, etc.
For example, I could create an alert group named "Project X" that consists of two SMS numbers and a Slack channel, and then I could assign that group to any alarms that are related to "Project X". In the future, when the members of "Project X" change I can just make changes to the alert group itself, rather than having to go to each alarm and add/remove recipients.
Thanks for your feedback, I just wanted to point out that with the recently added bulk update interface (https://headwayapp.co/updown-changelog/bulk-update-notification-recipients-54559) it's much easier to edit this kind of things.