How To Get An Addict Help Unwillingly

Hi every one,
i have a younger sister currently residing at my parants home, she has a drug addiction problem ( she doent think so ) she also has mental problems.. my mother and farther are stressed out and their health is now suffering, my question is how do you get help for her if she doent think she has a problem? and can you get help for someone how is unwilling to recive help?
and can you admit someone to a mental institution against their will... this is a very delicate situation and i am lost can someone please point me in the right direction, or any direction?

Thank you
Midgette
Post your question on the family board. You will get more answers.