Rehab appears to be agreeing with Kim Richards.

The Real Housewives of Beverly Hills star checked into an undisclosed treatment center December 5, and two weeks later, her sister (and RHOBH costar) Kyle tells Us Weekly she's "doing very well. Fantastic."

PHOTOS: Celebrity rehab centers

A former Disney child star, Kim, 47, briefly entered rehab in mid-2010, but declined to elaborate on her addiction issues. On Housewives' first season, a seemingly intoxicated Kim famously sparred with Kyle, 42, after Kyle called her an "alcoholic" during an ugly brawl.

VIDEO: Adrienne Maloof tells Us about witnessing the "sad" and "difficult" fight

Most recently, Kim's foe Brandi Glanville accused her of being on crystal meth, though costar Dr. Paul Nassif theorized that the cause of Kim's erratic behavior and slurred speech was a bad combination of prescription medications.

VIDEO: Kim Richards talks trash about Brandi Glanville

As Kim seeks treatment away from her family over the holidays, Kyle is anxious to put 2011's events behind her.

"I think I want a new watch [for Christmas], but I would settle for just peace and happiness and no drama!" she reasoned.

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