Non-defining relative clause

Dear Grammarians, I'd like to know whether these example sentences for the non-defining relative clauses are right or not. Why or why not?

Thank you very much.

1. The cupboard was full of glasses and cups. Many of them were broken.

The cupboard was full of glasses and cups, many of which were broken.

2. He had hundreds of books. He had read most of them.

He had hundreds of books, most of which he had read.