American Express Membership Rewards - charge credit additional holder

trying to answer a friends question and maybe a question of those on this forum as well.

Can one add a credit card to a charge card account for AMEX....i.e. one has AMEX Gold, PLT or Centurion and can they add a Blue or Starwood or Optima or Delta of Hilton etc... or something simliar as an additional card holder on that main Gold, Plt, Cent. account? Then the other holder's charges would be on main bill to main cardholder billing address right?, and they would have the option of paying those charges in full or in part? Thanks!

No.

Charge cards and credit cards are always separate accounts.

In some countries, the credit card's fee may be waived if you are already a charge card holder. But the cards have different account numbers.

On each of these main card accounts, you can apply for supplementary cards for people of your choice.