You can define a workflow to have multiple start points. Rather than having a single transition from the start shape to an activity, you can have multiple transitions to multiple activities.
This example workflow has been designed to start by categorising the application, but if the application is already categorised, then this step can be skipped. There are 2 transitions from the start to different activities. Not the open diamond at the start of the transition links. This indicates that there are conditions defined for the transitions. Normally, you would arrange that these conditions are mutually exclusive (i.e. only one of them will be satisfied) and hence the workflow will perform transition 1 or 2.
In the example above, transition 1 has a condition to check that Application Category is not set.
Transition 2 has a condition to check that it is set.
Hence when the workflow runs it will either go down transition 1 or 2. The completion condition of the Categorise Application activity is to ensure that Application Category is set. By the time we get to Assess Change Request, we know that Application Category will be set.
This example shows the conditions defined on the transitions, but they could instead be defined as pre conditions of the two activities, or a combination of transition and activity pre conditions. It also shows 2 alternative start activities, but in fact you can have as many as needed, assuming you can define the conditions to ensure the correct start is chosen.
At runtime, Flowset will consider each transition and start activity in turn until it finds one where the transition conditions and activity pre conditions are satisfied and then choose that one.