I'll be curious too. We were on a job that we were able to get two rf working (older rf remotes with Genie client). If your dad has the older style, when you get to the step that asks to input the rf code on the tv, do it to both remotes. This is how we got our older remotes to work.
I tried to add new smaller style rf remotes and couldn't get to work. They don't seem to program like the older ones by inputting rf code manually. They somehow get the rf code from the Genie, I think?