Kate Burton will pull double ABC duty this fall.

For one week, at least.

Via flashback, we can confirm that the Scandal star will appear on the September 25 opener as Meredith’s mom, Ellis, likely to help explain the presence of Margaret Pierce as Meredith’s half-sister.

On the Grey’s Anatomy Season 10 finale, Kelly McCreary’s Pierce (the new head of cardio) was revealed to have this connection to Meredith, with Richard Webber very likely being her father.

Shonda Rhimes recently said this storyline has been planned out for years, with various hints “layered” into past seasons and past episodes.

"We can literally go back and pull out moments of the show and I'm excited to do so, and point out where it was talked about," Rhimes told TV Guide. "It's not going to be so hard to do."

Grey's Anatomy Season 11 kicks off on Thursday, September 25 at 8/7c on ABC.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.