Download this zip file which includes:

• documentation for adding data from an external dataset (i.e. data NOT collected via the Observations survey in Survey123) to the Observations (survey) feature layer in AGOL, so that all Observations are reflected in the same Observations (survey) feature layer. 
• The model created for running this process for the specific dataset, a downloaded version of iNaturalist data, is attached as well.
• The presentation
• The recorded session

And for those who watched the live webinar or will be watching the recording, the Observations points were created which we saw in the relationships. The feature layer did not refresh in the Map quickly enough. When I re-added the Observations feature layer to the Map, the points were visible, as were the relationships as shown in the following screenshot. It just was not cooperating immediately because I was giving a live demo, of course!