Molly Shannon Molly Shannon

Molly Shannon has signed on to appear on ABC's The Middle, reports.

The Saturday Night Live alum, who recently appeared on Glee and the Cameron Diaz comedy Bad Teacher, will play the never-before-seen sister of Frankie (Patricia Heaton).

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As previously announced, Heaton's former on-screen hubby, Ray Romano, will appear in the Wednesday, Sept. 21 premiere (8/7c on ABC).