In Signals Notebook, it is possible to add a file as an external enumerator inside a parallel experiment, nevertheless, due to the configuration of some parallel experiment templates, not all experiments have an external enumerator and when selecting the “add content” button, the "external enumerator file" is not available.
Solution: In order to add an external enumerator, the parallel experiment must not have a previous enumerator. When a parallel experiment has an enumerator, it will make the “External enumerator file” option unavailable.
To delete the enumerator, select the enumerator in the Parallel experiment contents and click on the “delete” button.
Once the Enumerator has been removed, click on “add content” and select “External enumerator file”.