There doesn't appear to be a built-in way to send messages via the API. That said, an email with the correct subject could be generated, and the ticket email determined and included as well.
Get-ServiceDeskRequest-Id 12345|Send-ServiceDeskMessage-Text "Here is an email update to a specific user. It will be added to the ticket conversation."-To devyn.spencer@example.com-Cc worker.bee@example.com
New-ServiceDeskProblemRemove-ServiceDeskProblem# Unsure of correct verb to attach request(s) to a problemAdd-ServiceDeskRequestAdd-ServiceDeskProblemConnect-ServiceDeskProblemJoin-ServiceDeskProblemPush-ServiceDeskRequest
Not a direct consumer of an API resource - more of a convenience function.
# Rename a ticketGet-ServiceDeskRequest-Id 12345|Rename-ServiceDeskRequest-Subject "New subject here"# Add a prefix to an existing ticketGet-ServiceDeskRequest-Id 12345|Rename-ServiceDeskRequest-Prefix "FIX: "# Add a suffix to an existing ticketGet-ServiceDeskRequest-Id 12345|Rename-ServiceDeskRequest-Suffix "- DUPLICATE"