Hi.
Building an array of IDs is not possible without extensions like 🚀 RunJS 1.3.1.
If you are getting the list of IDs from inserts in a repeat, you can enable output of insert step, and send the repeat object itself as a param to the other library actions that you create.
If you are getting list of IDs from different sources, you can concatenate them into a single variable with a comma.
On the library action, you can just either always expect an array, or always expect a comma-separated-sting (single ID is also OK to consider as comma-separated).
Or, you can create two different inputs, one for aray and one for CSV/single value - and setup the code accordingly.
Let me know if I am completely off the point, and you are talking about something else. This is what I have understood. 