We have a reusable workflow in place that can be called from within a customer ticket. This reusable workflow calls a data connector that creates a back-office ticket and sets some values.
This way of working allows our 1LS agents to save some time as this workflow creates the back-office ticket, links it to the current customer ticket and even copies some values from the customer ticket to the new back-office ticket.
The other way around doesn’t work though, according to Intercom’s support.
The API only lets you link two tickets when the parent is a customer ticket and the child is a back-office or tracker ticket. That's why your current workflow works: the parent is the customer ticket and you create the back-office ticket from it. In the new flow, the parent is the back-office ticket and you're creating a customer ticket under it, which the API doesn't support.
In my opinion it would be a great enhancement if you would allow the API to create customer tickets and link them to an existing back-office ticket.