I have my dad's and my phone connected to the Command. Is there a way to prioritize them?

 

Usually it is the last paired phone that has priority. But the priority is decided when ignition is switched on. If both are not in the car at the time the radio turns on, the one in the car will be connected and remains connected even if the higher priority phone appears in the car later on.

I'm not sure actually if the order of priority changes if you manually select another phone from the head unit. I think this happened when I was driving my wife's car where her phone had priority. I did not double check but I think my phone remained at higher priority at the next switch on.