New app... Two users, one grill

Does anyone have ideas on how to allow two different users to connect the newer app to one grill?

On the old app my father-in-law and I were both able to have the app running on our phones. We had to get a new control board this past week and when I was in the dealer's store my phone was able to find the new control board but I didn't connect. I got the new control board put in and my father-in-law got his so connected to the grill but now it doesn't show up as an option to add in my app. The guy at the store thought that would be the case. I had read somewhere online there was a workaround for it but I can't find it again now anywhere!