What has been said so far but i will clarify the details. Any exec member using their avios points (whether travelling as a passenger or for someone else)must pay for the taxes on a card in their name. They retain control of the booking whether to change or cancel. In terms of status benefits the applicable benefits are based on the passengers status. So a blue purchasing a flight for silver or gold means the gold/silver still get free seat selection but the blue member has control of the booking. The other way round with the blue as a passenger the blue would not get free seat selection and the gold or silver has control of the booking.