Disappointing Addison's mom in order! And I'm about to watch last night's episode (I was at prom) so shhhhh...
Writer's Choice: Smoke
Erin's hands remind her of her mother's. And while Erin doesn't smoke, Addison finds that occasionally, her fingers move over her lips as if she's holding a cigarette. Her mother does smoke.
Her mother smokes, elegantly, in fact, a black-and-white, Audrey Hepburn kind of action, that relies less on the tobacco and more on the appearance of a cigarette hanging loosely between her fingers. She smokes as though only to be social, as though she can quit, right there, and not need the nicotine tomorrow.
It's only after meeting Erin that Addison realizes that yes, her mother does need the nicotine tomorrow.
Reference: Audrey Hepburn's smoking is probably most remembered in Breakfast At Tiffany's, which is based on the book by Truman Capote. Both are excellent.