Which is better - with which or with whom?

Question

In German, is there a preferred way of saying with whom or with which?

For example,

Die jungen Kinder, mit wem ich arbeite, sind schikaniert worden.

The young children, with whom I work, have been bullied.

Or is this construction better? It seems less personal to me, as if I were not to know them.

Die jungen Kinder, mit den ich arbeite, sind schikaniert worden.

The young children, with which I work, have been bullied.

Answer 1

The sentence requires a dative relative pronoun which in this case would be denen because die jungen Kinder is plural. So correct would be

Die jungen Kinder, mit denen ich arbeite, sind schikaniert worden.

Answer 2

German does not have distinct personal pronouns like English, only relative pronouns, with the exception that damit, womit cannot be used of persons; mit dem or mit den is used instead. You have to rely on context.