Firstly - IFA's can only be offered if a modern award applies.
Secondly - Please read section 144 to 145 of the Fair Work Act.
Thirdly - and IFA requires the EMPLOYER to ENSURE the arrangement results in the employee being better off overall had the employee not entered the agreement in the first place (s.144(4)(c).
Fourthly-the agreement can be terminated by either party and
Finally - An employee does NOT have to enter into an IFA, its voluntary and of major concern is the employee has a workplace right (s 344) and an employer MUST NOT exert undue pressure or influence to agree to or terminate an IFA.
If your employer makes a reduction in pay or other entitlement as a result of not making an IFA then the company is injuring the employee by entering into an 'Adverse Action' and good bye
HR career if you are found guilty of such action and contravention. Be aware that not only can a director be personally liable for an action, a
HR manager or alike can equally be personally liable for making or causing an adverse action or workplace right.
Basically, the parth you are about to travel is a dangerous one. and i dont see the IFA being better off overall should the employer remain as is, as the wages and terms paid, al beit above award, are a customary practice (Custom and Practice) and there would be other industrial action or court action that can be taken against the company.
Over to you