(pronoun) when the person is the object of a verb or preposition
Note: This is the grammatically correct pronoun for the object of a sentence. However, in everyday conversational English, the sentence is commonly restructured and who is used as the pronoun for both the subject and object.
1. I am looking for someone with whom I may discuss this concern.
2. I have a presentation to give at work tomorrow in front of the whole division, many of whom are experts in this area.