I just broke up my household account for point utilization purposes. One of the members was under 18 and when removing him from the household account it automatically canceled his account and put the points in my account.
This might work for getting the points for flights flown by others. Have them create a new FFN with a birth-date making them under 18 and add it to their reservation. Add them to your household account and then kick them off.
What do you think?