I would train their OD to prolific first for both of them, and then proceed by training Handling for three more points. Jump Range and Jump Shot might be nice too. Passing and Driving might come last, and their JS is already quite nice for 18-yos.
You can train both of them parallelly, the second one will always be more of a SG than the first, so their relative roles won't change, and both will profit from all the skills you want to train either one.