The News Journal of Wilmington reports 40-year-old Jessica Ewin of Dover was charged Friday after police said she adulterated the milkshake with what she thought was a homemade dose of the poison ricin.
Court documents say Ewing told her 8-year-old daughter to urge her father to drink the concoction. Police said Ewing and Michael Funes were involved in a custody dispute.
Ewing's current husband didn't return calls seeking comment. Bradley Martineau previously said the poisoning claims were lies.
Ewing was charged previously with interfering with child custody after collecting her daughter from her Wyoming school last month and visiting relatives in Pennsylvania.