Toyota Injector specs:

The early Toyota 4A-GE engines came with Low-Z 2.3Ohm injectors wired in parallel pairs with two 2 to 3Ohm resistors in series with each pair, for some reason these pairs are connected in parallel which ends up giving a 1ohm value when measured.

While it is very easy to fill in h[] table to switch more than one (up to 8) injector outputs simultaneously. See GenBoard/Manual/DigitalOut/Table. However, connecting several injector in parallel is a bad idea. The FETs share the load fine (and they are spec-ed to >10A anyway). On the other hand, the flyback does not share the load well. In the worst case only one channel bears 95% of the whole load (the channel with lowest flyback voltage), the other channels only flowing marginal current (because the diodes have -2mV/K temp coefficient, so if one diode-set gets more current, the break-voltage will drop -2mV/K because of the heat, so it will get even more and more until it will bear all current). One channel can bear appr. 4A if PWM is not used, and 2A if PWM is used.