I have these two sentences as examples:
They seem a little concerned about the direction [that] we're taking.
If I'm not mistaken, about the direction we're taking is an adverb prepositional phrase because it modifies the adjective concerned, and prepositional phrases can have multiple elements inside it.
The thing [that] I wish for most is that people would all just get along.
Now the focus on the subject, so I wish for most seems to be describing the thing.
Are both of these parts of the sentence relative clauses because of how they modify and follow nouns? If so, a that could be introducing them, right?