Merging Tickets
It's common to merge Zendesk tickets from time-to-time to group multiple Slack messages into the same Zendesk ticket. When tickets get merged, all replies from Zendesk will become threads on the Slack message corresponding to the ticket being merged into.
When merging tickets, it's important to uncheck the Requester and CCs can see this comment box to prevent comments from being posted back to Slack.
Don't forget to uncheck the Requester and CCs can see this comment box when merging tickets.
Slack Replies From Merged Tickets​
When merging tickets, you're choosing a single Slack message to become the "parent message" for the conversation. It's assumed that all replies from Slack will be under this same parent message. If a new thread is started on a different parent message, it will be created as a new follow-up ticket in Zendesk.
Reduce Manual Ticket Merging​
While there will always be a case for using a supporting merged tickets, adjusting the Same Sender Message Threading timeframe setting can help make this more automatic.