Populate timeseries series_id in ontology object without a backing dataset

We have a workflow, where we are triggering investigations, and the investigations are created using actions. I would like to add a timeseries attribute to the object so that we can use them in the interface, however we don’t have a backing dataset, so i wanted to do this using actions.

I tried adding it using a form in an ontology action, but the form interface shows a message that series can’t be edited through forms. I also tried creating an ontology edit typescript fuction, but the series attribute is not edittable in the function. Is there a way to do this?