This rule prevents parties from changing the importance of written contracts with oral or tacit agreements that are not included in the original contract, the latter impairing their integrity. This means that, when a contract is available in writing, subsequent agreements that are not entered into in writing are not proven in a contractual dispute. There are, however, several exceptions to this rule. However, the High Court decided that this would only apply if the terms of the guarantee contract complemented or complemented the main agreement. If the security contract is not in accordance with the main agreement, the conclusion of the main agreement does not, in itself, constitute a valid consideration in support of the security contract. In this way, the main agreement is essentially considered to be the most important of the two agreements and, therefore, the terms of the guarantee agreement cannot deviate from the promises contained in the main agreement. A security contract, if forged between the same parties as the main contract, must not be contrary to the main contract. In other words, if the term was agreed before the formal contract was concluded (but was still in place and could not be executed before the end of the second term), the first term will remain eligible.  In essence, security contracts cannot contradict an element of the main contract or the rights that flow from it.  Ancillary contracts are an exception to the practice of contractual doctrine, which states that a contract cannot impose obligations or rights on a party not related to the contract.  However, in cases where a security contract is entered into between a third party and one of the contracting parties, the Court may authorize rights or obligations to the non-contracting party, as outlined in the previous unauthorized Donoghue/Stevenson case.  A support contract is generally a one-time contract that is agreed against the party whose advantage is exploited by the contract to conclude the main or principal contract, which sets additional conditions for the same purpose as the main contract.  For example, an ancillary contract is entered into when one party pays the other party a certain amount for entry into another contract.
An ancillary contract may be entered into between one of the parties and a third party. A support contract is a contract by which the contracting parties enter into or promise another contract. The two treaties are therefore linked and can be applied, even if they are not a constructive part of the original treaty.  In JJ Savage and Sons Pty Ltd v. Blakney, a mere expression of opinion was not deemed sufficient to be kept as a promise. In Crown Melbourne Limited v Cosmopolitan Hotel (Vic) Pty Ltd, a statement from a landlord to the tenants considered when negotiating a lease agreement that they are “supported during the extension” would not bind the lessor to offer another five-year lease.  Ancillary transactions are often used by parties in a number of commercial transactions.