sorry, I read your sentence too quickly. if someone asks the question: "where is he" and the answer is "he is in with the BoD" it means he is meeting with them.

A Board of Directors is a group of people. you use with to say you are part of a one or a group. you are with your classmates, with a team, with your neighbors. you use "in" to signify a place. for example, you are in China, you are in your home, you are in a theater. "with" usually implies time aspect. for example, you might say "I was with my best friend last night". if there is no time element, you could us "on". for example, "he is on the board of directors". there are some exceptions and also other ways to signify you are "in" or "with" people, but this is the general rule.

"in with" is part of the idiom "get in with", which means to become involved with a person or group. That involvement might provide influence and power.