Sorry, not sure what a HHA is, but I suspect I don't have one.
It is a House Hold Account. If you have one your miles will be deducted per ratio over the members of the HHA.
If there has been a mistake in my favour I don't what to draw too much attention to it. A few years ago, probably five or six, I booked LHR-SFO-LAX-LHR using an Amex companion voucher. As it was an open jaw ticket I had to book on the phone and the miles were never debited from my account. I didn't make too much of a song and dance about that...
I made quite the hoopla when I discovered that I could book return in J to the USA for only 50K. This must have been about a year ago since I am leaving this Thursday.
So, spill the beans!