Hybrid heavy-duty vehicles powered by multiple fuel cells (FCs) offer opportunities to improve energy efficiency and support sustainable powertrain operation through powertrain-level optimization. This study investigates optimal gear shifting to reduce the electrical power demand of the electric machine (EM) and optimal power distribution among multiple FCs with different ageing states. A longitudinal vehicle model determines the wheel power demand and propagates the operating point backward through the drivetrain. An optimization-based gear-selection strategy identifies the gear that minimizes the required EM power, while a closed-form optimization method optimally distributes a given total FC power demand among multiple FCs according to the specific electrical energy output and remaining useful life of each FC. An active-set procedure enforces FC operating limits. The methods are evaluated using a Paris–Munich ESCALATE drive cycle and several FC age configurations. Optimal gear selection reduces EM power demand by up to , while optimal FC power distribution reduces hydrogen consumption by up to  compared with equal power distribution. The optimized allocation also reduces differences in FC ageing states, potentially enabling more coordinated maintenance and sustainability benefits.