Model Start Event Cascade through BPMN

Question

I'm trying to model the following (simplified) workflow. Each start event has a route to the Main Task as well as an alternative route which will trigger the "previous" start event.

My problem: if Start Event 2 is triggered through a path from Start Event 3 it should not be possible to trigger Start Event 1 any more (red path): 3->2 is ok, 2->1 is ok, but not 3->1!

What would be the "right" solution here? Should I create an alternative Start Event 2 when it's triggered through Start Event 3 (seem to be redundant). Or should I solve this somehow through a logic gate if triggered through Start Event 3 then ... else ... (seems to be over complicated). Or is there a better solution?

PS. I tried to find a better stack exchange site for modelling but it seems 99% of the questions regarding BPMN are posted here. But I'm open for suggestions.

Answer 1

Based on Simulat's answer I found a alternative solution which I think is the better fit. The red path should not be possible because of the logic gate with the red circle (the top path is only viable if Start Event 3 has not occurred).

The problem I have with Simulat's answer are the intermediate events and the event based gate. Since there are no "real" events on those points so I think they should be xor logic gates, but I'm not sure. Feedback is welcome:

Answer 2

First of all, Start Events must not have an incoming Edge. It is not allowed by the BPMN standard. So you should replace your Start Events 2 and 3 within the process with intermediate Events.

The decission logic to skip or execute the Intermediate Event now representing the event of what was before Start Event 3 could be implemented in an Event Based Gateway, describing on the Edges which path to take under which condition.