I've booked tickets using my miles for others and I've booked tickets using family member's accounts for myself. No rules against it. Also remember the miles don't expire. Though, like the USD, Skymiles are likely to lose value over time so it's best to spend the miles sooner than later. You can also buy things with miles. Transferring miles is the last thing you should do, as that essentially wipes out the value of them once you pay the penalties.