It was previously not kosher to use your HHA miles for someone who didn't live at the same address. That probably didn't stop people from doing so... Nonetheless, I welcome this announcement:
Dear Mr jib71,
We're delighted to bring you a great benefit of being an Executive Club Member.
We've enhanced our Household Account offering, so you can now spend your household Avios on up to five family and friends that do not live at the same address as you. Simply add them using your new Family and Friends list.
As with your Household Account, you can book reward flights for them with Avios. And since the details of your chosen five will be saved and filled in, you'll be able to make the bookings quickly and simply.
Log in at ba.com and you'll find 'My Family and Friends' as an additional option under 'Manage my account'.