Former Peak Practice actress Saskia Wickham will play Anna, mum of Dodger, Will, Liberty and Sienna Blake.
She tells her children how Patrick Blake was abusive until she fled with Dodger, leaving his twin Sienna behind. He denies the accusations.
An insider told the Daily Star Sunday: "Anna has a lot of questions to answer. Her children are going to struggle with her reasons for leaving."
Anna will arrive in the Channel 4 soap next month.
James Atherton, who plays Will, recently teased that there will be "hell to pay" if Texas Longford (Bianca Hendrickse-Spendlove) discovers the truth about his recent fall.
"Will basically uses the fact that she thinks she pushed him down the stairs to manipulate the situation," he said.
"He wheedles his way into her life one way or another, and out of guilt Texas reciprocates to him and panders to him - and he keeps pushing his luck to see how far he can get."
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