Update. I called the dealer and they told me I had to buy a new fob and they could add the sales code and program the new fobs. So I make the appointment and drive a hour to the dealership and they then tell me they don’t know how to do it and don’t think it can be done. They told me we have never done this before. I have another dealer to try.
@Jimmy07 have you done this before?
Not with keyless entry, but it’s all possible. Here is a pic of the instructions for adding the tailgate damper and remote tailgate release. The remote tailgate release option is very similar to the remote keyless entry option, in that, all it requires is the correct key fob, and the sales code.
They would follow these same instructions, except, on #2 under add sales code, they would add the sales code GXM instead of JKR. Everything thing else in the instructions are the same. Same goes for remote start and it’s sales code XBM.
EDIT to add: If you get the correct remote, you could do all three in one shot- JKR, GXM, and XBM.