At first Anne Frank is warm to Mrs. Van Daan and the Van Daan family, saying they've become like one big family. However, as time goes on, things change. If the Diary had been fiction, the change for the worse would have been foreshadowed by the arrival of the Van Daan family a day early, with Mrs. Van Daan carrying her chamber pot in a hatbox, betokening stubbornness and an entrenched mode of thought.
If it had been been foreshadowing, it would have been exactly right. Mrs. Van Daan turned out to be selfish and highly opinionated and intrusive. Even though Mrs. Van Daan was hard working, she failed to make a lasting good impression by her continual know-it-all, advice-giving ways, a trait she shared with her husband, incidentally.
Anne Frank summed up her opinion of Mrs. Van Daan by saying,
The Van Daan motto: 'We get the best, we get it first, we get the most.' I've gained some insight into human nature since I came here, which is good, but I've had enough for the present.