In third person, characters can say what they think about a situation and the narrator can simply report what they say.
For example, here are two characters who disagree:
Bod looked up at Silas, pleadingly, but there was no sympathy on Silas's face. He picked up his bag and said, "You will be in good hands with Miss Lupescu, Bod. I am sure that the two of you will get on."
"We won't!" said Bod. "She's horrible!"
Each character expresses their opinions and judgments in dialogue.
Basically:
More specifically, the disagreement is about their assessment of whether or not Bod will get along with Miss Lupescu while Silas is away:
What are Frederik and Ilse disagreeing about?
"You mean the mirror my grandmother gave us?" Frederik said, pointing at the shield-like disc above their bed. "It's a priceless heirloom!"
"It's trash, I hate it, and I want it gone," said Ilse.
Cody and Alonso both have opinions, but are they agreeing or disagreeing?
Cody shook the trucks, roughly, then handed the board back to Alonso. "Your bushings are done, bro. You need to swap 'em before you bust a knee."
"I don't have any money," said Alonso. "It sucks."
You have to make a perspective shift into third person:
It's one thing to report what a character says, but what about describing what they think or feel?