[Removing an object tangled in hair]

Is there a tutorial or suggestion of how to remove an unwanted object that is juxtaposed in a subject's hair? For example, taking a picture of a model but having an unwanted person who might be sitting behind the model yet that person is blended into the model's hair. When I try to remove the object, or in this case the person, I get a mess of tangled hair, etc. Many thanks to any contribution.