@Oran, the GUI does not deliver the capability to automatically update or upload an instrument list. But this can easily be done using the API.

The API does not give you the possibility to upload a new file to replace the contents of an existing list, but it allows you to manipulate an instrument list, by individually adding / removing instruments from the list. As I understand (from your other query) that you are using Java, you can look at the Java code sample DSS2Instruments which shows how to get an instrument list ID from its name, and how to add instruments to an existing list (referenced by its ID). It is also possible to delete instruments from an existing list, see here.

Depending on your use case, it might be easier to create a new list every day, and then either update the schedule to use the new list ID, or simply create a new schedule referring to the new list. The API also allows to delete the previous list and schedule. The Java sample DSS2ImmediateScheduleTermsAndCondition shows how to do most of these actions.