In short, the answer is no. Section 459G of the Corporations Act requires an application to set aside a statutory demand to be supported by an affidavit within 21 days of service of the demand. Usually the facts for the setting aside application are known within the 21-day period. 

What should you do when there are unknown facts at the time of filing the application to set aside? For example, where there are inaccessible or unverifiable documents, or you are waiting on third parties to provide materials (eg accounting information), or further discovery is required?