What does 'manage that much' mean here?

Question

What does 'manage that much' mean here? And, please, explain why 'much' is used in this case and its meaning.

Then the door to the cafeteria/gym opened, and a Mr. Jenkins came out. Which Mr. Jenkins? There was no telling them apart. Meg looked to the cherubim, but he had de-materialized again, leaving only a shimmer to show where he was.

Mr. Jenkins came to her. She checked his shoulders. There was the dandruff. She went closer: smelled: yes, he had the Mr. Jenkins smell of old hair cream and what she always thought of as rancid deodorant. But all three of the Mr. Jenkinses could manage that much, she was sure. It was not going to be that easy.

From A Wind in the Door by Madeleine L'Engle.

Answer 1

In looking at this:

• The passage is talking about one of three people claiming to be the real Mr. Jenkins.
• Meg is trying to determine if the one who appeared is the real one or an imposter.
• She sees that he has dandruff and smells of old hair cream—just like the real Mr. Jenkins.
• It was not going to be that easy refers to being able to tell them apart because of this detail.

But all three of the Mr. Jenkinses could manage that refers to the ability of all of them to have dandruff and smell of old hair cream. Obviously, the real Mr. Jenkins can manage to get all of the details about himself right. But what Meg's saying is that these particular details are pretty obvious, and not something that would be difficult to pick up on and emulate. Whatever test she's going through to tell them apart, is bound to be more difficult than just observing this simple detail.

In other words, telling them apart will surely not be as easy as looking for signs of dandruff and detecting the smell of old hair cream.