Story highlights Alan Thicke's sons, Robin and Brennan, have filed a petition against their father's third wife, Tanya Callau Thicke, over his estate

Thicke's sons are the co-trustee's of their father's living trust and claim that Callau is disputing the prenuptial agreement she signed in 2005

Callau's attorney tells CNN this is a "smear tactic to bully" his client

(CNN) Alan Thicke's sons are gearing up to battle their father's widow, Tanya Callau Thicke, over his estate.

Thicke's two eldest son, Brennan Thicke and musician Robin Thicke, filed a petition Tuesday in the Los Angeles County Superior Court after they allege that Callau disputes the prenuptial agreement she signed ahead of her marriage to the "Growing Pains" star in 2005.

"Now that Alan is dead, Tanya claims there are numerous problems with the Trust and the Prenuptial Agreement," states the Thicke son's attorney, Alex Weingarten, in the petition obtained by CNN.

The court documents also claim that Callau "threatened to make her claims fodder for 'tabloid publicity' unless the Co-Trustees agreed to participate in a mediation and succumb to her demands."

Callau's attorney, Adam F. Streisand, told CNN in a statement that Robin and Brennan's petition is "distasteful" and a "smear tactic to bully" his client.

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