Mr Busch had claimed in a You Tube video posted on August 22, 2010 that his mother and Mr Bailey had slandered him in the media. He was also critical of the pair's not guilty plea after keeper Dalu MnCube was mauled to death by a big cat in May 2009.
In December, the Whangarei District Court ordered Zion to pay $60,000 reparation to Dalu's widow when the park pleaded guilty after earlier pleading not guilty to two charges of failing to take steps to prevent a hazard and failing to take steps to prevent harm.
Mrs Busch and Mr Bailey's statement of claim says Mr Busch made defamatory claims to do with events on the day Dalu died.
The statement also says Mr Busch had claimed Dalu was going to be used to do a television series doing "my job".
In the claim, Mr Barter said the You Tube link was also accessible on Mr Busch's Facebook page, Twitter account and his website, the contents of which Ms Ward managed.
Mr Barter has asked the court for a permanent injunction preventing Mr Busch and his spokeswoman from making or publishing statements relating to his clients, or any companies associated with them.
He also seeks an order that they remove the video clip and all its links containing the defamatory statements.
Auckland District Court will hear the case at the end of February.
Meanwhile, the park and its assets can now be sold after Mrs Busch consented to the sale.
The sale, however, would not include 36 big cats as their ownership is expected to be decided by the High Court in Whangarei next month.
Receivers PricewaterhouseCoopers had received an offer from an interested party to buy the park - details of which were suppressed by Justice Mark Woolford at the High Court in Auckland on Wednesday.
Mrs Busch's lawyer Evgeny Orlov asked the court to view the sale agreement because he was concerned the offer was from his client's son and Lion Man Craig.
Citing commercial sensitivity, Justice Woolford allowed the lawyer only to see an abridged version of the document - with names and figures left out.
Mr Orlov took exception to that but Justice Woolford said it was normal practice to allow confidentiality in such matters, especially given the sale had not been completed.
PwC lawyer Justin Toebes said the hearing on Wednesday was nothing to do with euthanising the animals but was normal process in ending a receivership.
The case was adjourned to next Friday but if both parties agree to a deal outside court, then next week's hearing will not proceed.
The High Court in Whangarei will next month hear arguments on who owns the animals.
An injunction obtained by Mr Busch prevents the sale or transfer of the big cats.