OH and I created a HH account about 3 months ago. Today I added another member (child) to the account, and it seemed to go through fine and he is showing as a member of the HH although he hasn't got any miles of his own yet.

Afterwards I saw the rule about no changes for 6 months at a time, now I am wondering if I have screwed up. Would it have rejected the new membership there and then? Is it 6 months, as measured from a change, not from
HH account creation? I don't want to let him accrue mileage if it'll suddenly get declared invalid and he'll lose them. (AIUI because he's a child, if he leaves the HH account he cannot hold his miles in his own right).