How to add the users in a project to the watcher field automatically?

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1

I got a requirement which is to add the users in a project to the watcher field automatically. And remove the user from the watcher field automatically while the user is removed from the project. In short, the watcher group field always filled with the project members. And the watcher group can add a user manually.

Is there any solution to achieve it? Marketplace plugin, REST API or SDK is workable?

2

Eventually, this requirement is implemented via the “Add or Remove Watchers” post-function provided by the Workflow Magic Box plugin.