Dansdad, so you are saying Disney is now allowing minors (age 17) make a reservation in Another person's name, and use a different credit card (not in either one's name), and do online checkin.
The person asking has asked this question, there different times in these boards, just worded differently, hoping for the "answer" they want.
Person making reservation as "lead" guest and two minors "who have credit cards (age 17). They want to use a credit c a rd that one of the 17 year olds have.
Unless laws have changed (which honestly they might have) a minor cannot enter into a "contract" or be responsible for paying "incidentals".