Legal Question in Criminal Law in Michigan

Michigan is a "one party" state, meaning that it is legal to record a private conversation if at least one party involved in that conversation knows it is being recorded and agrees to it being recorded. Some other states require all parties to know about and agree to the recording. If the person doing the recording in Michigan is not "in" the conversation but just near enough to listen in on others' conversation then that is not legal because the person doing the recording is not "a party to the recording" ... unless someone in the conversation knows in advance it's being recorded and is ok with it.