You hit the hail on the head. HKS had to be worried what ANS might say. He already had a program in place of keeping her in his sight and as isolated as he could manage.
So when did she FIRST talk to the police and give a statement. How many tapes did Howard make that he is holding back until the right moment?
Was Howard present when she gave her statement? It's not supposed to work that way if he was. She wasn't under arrest.
If she had a memory loss, how could any statement even be valid. My guess isn't that the whole "message from the grave" will be about Howard and how wonderful he was and blah, blah, blah...
As far as I'm concerned, it simply can't be valid. It's called "undue influence".