It already says, "Unofficial Narcotics Anonymous message board . . . . . ."
Maybe the Unofficial should be bold or a larger font.
Another website uses the following disclaimer:
"These are member's personal views. NA has no opinions on outside issues and is not affiliated with any outside websites."
Any 12-Step message board will have the same problem as they, for the most part, have the same traditions.
Just a suggestion.
FFL