Personally, I would create a new dataType for External References and then connect it with the User. That way you can use a repeating group to display their external references and it can vary depending on which ones they have. If you are a new user to Bubble, this might not be the easiest thing to do, but I think it’s a good concept to learn.
That’s a really good call – I hadn’t thought about how I would display the data, and the point you’ve made about using a repeating group to do so makes so much sense.