Are in on is a phrase that means being involved or having knowledge of something. There are several synonyms that can be used in place of this phrase, such as "in the loop", "privy to", "aware of", "informed about" and "acquainted with". Each of these synonyms conveys a sense of being included or being informed about something. "In the loop" suggests being part of a group or conversation, while "privy to" implies having exclusive access to information. "Aware of" is a more general synonym, indicating simply that a person has knowledge of something, while "informed about" and "acquainted with" indicate deeper understanding or familiarity with a subject.