I am defining the symbology in the AGOL Web Map. Really "crashes" is a poor choice of words. there are two problems with the feature class (when dealing with a 1:many relationship):
1). If I try to create a new feature I get a pop up that says Update failed Updates could not be sent.
2). If I select an existing feature and then press the edit feature "button" I get a pop up that says "Unfortunately, Collector has stopped" and I click OK and collector bounces back to the main menu and I have to refresh it so that the map that I was working on will show up again.
If I show details and scroll down to the views, I get all the related table entries, and I can even create a new one with no issues...most of the time. Since I posted this I have been in contact via email with a developer and they say that 1:many related tables is not supported at this time. The 1:1 is working OK, it is not intuitive but with a little tutorial I should be able to get my more technologically inclined people up and running with it.