Pretty sure is the same as "I don't know" in court. The question would be: "Have you ever seen Anna's will?" It's a yes or a no.
Howard wouldn't DARE to give something nasty about anyone to ET, in fact, just the opposite.
So, he's looking for happy time pictures of him and Anna...but there aren't any...
Any "Happy" pictures were taken by Larry and they don't include Howard except for background. Wouldn't it be "sweet" if Anna had sent Larry a picture of her and the baby and there was a kiss on it". (Ah, DNA)
Remember, Larry said that some of the things that he bought the baby were there the day he fed her. If Anna hated Larry so, they wouldn't have been there. Howard didn't know what Larry bought but Anna sure did.