Originally Posted by
mahasamatman
Not true. With BAEC, when one person has activity, it extends the expiration for all family members.
Wrong. There has to be activity in each individual account to preserve that account's miles.
A redemption pulls miles from each account, so a redemption counts as activity for each member, but if there's no activity in an account, that account's miles will expire. Earning miles in one account does nothing to extend the expiry of any of the others.