Hi Peter. A sequence can only have one trigger, but there's a pretty simple way to achieve what you need using the step which can call another sequence.
You should create the main sequence which is triggered by one of your cameras.
Then, create another sequence for each of the other cameras as follows:
- Triggered by camera
- Call the main sequence using this step type
That way, you will only need to create the main sequence once, and can reuse it for each of the other cameras.