Another word for whom

Actually, she knew very little about the man with whom she had promised to spend the summer.

He saw a gentleman whom he presumed to be the director, and told him about Helen.

At the porch he met two of the landed gentry, one of whom he knew.

How different if must be, he thought, making love with someone for whom you really cared.

Here in dwells an old man with whom I would like to converse.