You can't have it both ways: you can either report a suspected misclassification to the department of labor (either the federal or your state's department), for investigation and possible action, which may result in you getting the appropriate compensation (e.g. the employer share of taxes) but will also result in liability or your brother or his company; or you can leave this alone. There is no way for you to get compensation or have the situation corrected without exposing him or his business to liability.