To have two commanders, both must have the partner ability as the game begins. Losing the ability during the game doesn't cause either to cease to be your commander.
Thrasios, Triton Hero
The nonland card you reveal will be the card you draw.
If something refers to your commander while you have two commanders, it refers to one of them of your choice. If you are instructed to perform an action on your commander (e.g. put it from the command zone into your hand due to Command Beacon), you choose one of your commanders at the time the effect happens.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Josu Hernaiz
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
