> Sarah and Tamara are best friends. Chaim & Rivka are boy friend and
> girl friend. Sarah & Rachel are sisters. Tamara & Rivka are sisters.
>
> Chaim (who seems to have gotten his info from Rivka) phones Rachel and
> tells her that Tamara is harming herself for eg taking drugs/ binging
> or a similar damaging activity. Rachel tells Sarah who then tells
> Tamara who in turn denies the situation (but could be lying) and is
> angry and upset.
It is proper to approach the subject who people want to help. However, it
sounds like Sarah told Tamara that Rivka, Chaim and Rachel were talking
about her, which is Rechilut (and therefore forbidden). Also, it sounds
like Rivka, Chaim and Rachel were gossiping more than trying to resolve
the situation, or one of them would have discreetly spoken to Sarah in the
first place; telling more people than necessary is a violation of Lashon
Hara.
One person should discreetly speak to Tamara and express concern without
mentioning names or rumors ("I'm concerned - are you taking drugs?").
This should only be done after facts are verified (i.e. did the original
gossiper see Tamara take drugs, or repeat another rumor that should be
tracked down?). Rumors should not be brought as "evidence" when
approaching Tamara unless they are absolutely verified.
The purpose is to help Tamara either stop hanging around with a crowd doing
drugs (which may be what started the rumor) or stop doing drugs herself.
Efforts are most effective when Tamara is not embarrassed by being told
lots of (or any) other people are talking about her.
Hope this helps,
Ellen Solomon