Work Instance Query
The Existing Instance Branch toolbox item is a conditional block which will give you more granular control over what to do with a workflow if you have manually changed the phase of a work item, which can occasionally lead to running a workflow more than once or perhaps not at all.
Common Uses
It has three potential outlets which check the current status of a workflow:
- Already complete - This process has been run before, to Plan Complete.
- Already running - Another instance of this process is already running.
- Never run - This process has never been run.

If you need to move the phase of a work item manually, you can use a block like this to avoid triggering a process that has already been run.
For example, if a workflow triggers some communication to a client after a work item passes a particular phase, you may need to move the work item back to a previous phase for certain business needs. In such cases, you can use this work item to control whether future actions are triggered again, skipped, or check if the process is already running.