Two lawsuits have been lodged by company Alyssa Treasury Services Limited. Its lawyers say representatives of Terri signed contracts promising the money to other companies.
The contracts are said to have been signed in March and August - well after Steve's death in September last year.
Terri and her manager John Stainton, also formerly Steve's business partner, have denied knowledge of the lawsuits and the contracts they allege.
Stainton commented: "We've no bloody idea what they're about."
The first claim was lodged at the Victorian County Court on November 22 asking for AUS$2.5m from Australia Zoo and the Steve Irwin Family Trust. A second, requesting AUS$60,000 from Terri personally, was submitted on December 7.