Maintaining a "normal" (that definition is going to vary from family to family) family dynamic, or at least giving it your best shot, can help the whole family cope with family addiction.
Don't ignore the problems of addiction -- that kind of "everything's fine" behavior sets the stage for denial and enables the addict. Recognize it but don't hold the disease up as the center of the family universe. For example, if your wife used to attend your daughter's soccer games but is now at a residential treatment facility, try to be present at as many games as you can. If you're the parent of a teen with an addiction, be sure the addict isn't the center of your attentions. Recognize that you'll need to devote time to that child's recovery process but not at the expense of the time spent with your other children.