the best business partner exluding family would have to be a long life friend ( best friend) someone you have know all your life, that would be your best shot.
although no one can ever be 100% trusted it may be cynical of me but the only person you can rely on, trust and ultimatly confide in is youself.
then you could always go down the blakmail route if you have something on them then they have to do what you want lol your the Master pulling the strings bending and breaking them to your will HAHAHA...