**To add a source identifier to a subscription** The following ``add-source-identifier`` example adds another source identifier to an existing subscription. :: aws rds add-source-identifier-to-subscription \ --subscription-name my-instance-events \ --source-identifier test-instance-repl Output:: { "EventSubscription": { "SubscriptionCreationTime": "Tue Jul 31 23:22:01 UTC 2018", "CustSubscriptionId": "my-instance-events", "EventSubscriptionArn": "arn:aws:rds:us-east-1:123456789012:es:my-instance-events", "Enabled": false, "Status": "modifying", "EventCategoriesList": [ "backup", "recovery" ], "CustomerAwsId": "123456789012", "SnsTopicArn": "arn:aws:sns:us-east-1:123456789012:interesting-events", "SourceType": "db-instance", "SourceIdsList": [ "test-instance", "test-instance-repl" ] } }