2018-07-13 : If you don’t control your commander as the lieutenant ability resolves, you won’t get its effect.

2018-07-13 : If you have multiple commanders, you need to control only one for the lieutenant effect to happen.

2018-07-13 : The lieutenant effect happens only once each combat, even if you somehow control multiple commanders (perhaps because you have two commanders with a partner ability from the Battlebond™ set).