Perhaps some of the RA"s from the other board can offer their insight on this here as well, but my opinon is, yes al anon will still help since she's still an addict that just doesn't drink.
Because she's not drank for 15 yrs, doesn't mean she's in recovery. It means she doesn't drink. Unless an addict is working their steps and staying active in recovery, they still have the traits.
Addiction is the symptom to an underlying mental issue, so unless she's dealt with that, then she's not really in recovery/