About appositive clause.

Hi!
- My most famous relative of all, the one who really left his mark on America, was Rob Sussel, my great-grandfather.
Is the bold an appositive clause, please?

No, as it's not a noun phrase. But it does have the same general function.

However, "my great-grandfather" is.

- My most famous relative of all, the one who really left his mark on America, was Rob Sussel, my great-grandfather.
Another sentence.
- He is a strict but kind-hearted father, one whom the children respect but are afraid of.
What are THE ONE AND ONE in the above sentences used for while the sentences are still meaningful without them, please?

Actually, I see "the one who really left his mark on America" as a noun phrase. I may be wrong about whether to call it a phrase compared to a clause or something else, but it functions as an appositive, as does "my great-grandfather."

hoangkha said:

- My most famous relative of all, the one who really left his mark on America, was Rob Sussel, my great-grandfather.
Another sentence.
- He is a strict but kind-hearted father, one whom the children respect but are afraid of.
What are THE ONE AND ONE in the above sentences used for while the sentences are still meaningful without them, please?

Click to expand...

the one who
The first sentence is called a noun phrase: , the one who really left his mark on America , was Rob Sussel
In the second sentence, I see it isn't necessary to say the word one:

He is a strict but kind-hearted father, whom the children respect but are afraid of.
It is called non-defining relative clause

My most famous relative of all, my great-grandfather, the one who really left his mark on America, was Rob Sussel.
my great-grandfather is called a positive clause.
the one who really left his mark on America, it adds extra information my great-grandfather.