The use of cestui that is the person to the advantage (i.e. the use) of trust. The cestui that trust is the person who is entitled to just, unlike the legal succession in the trust. So if land is allocated to A for the use of B in the trust, with the rest to C when the trust ends, A is the trustee, B is the trustee and C is the trust. Normally, B and C are the same person, so the terms are usually synonymous. Both have been virtually replaced by the notion of “beneficiary”, mainly because of their cumbersome nature in general fiduciary law. Cestui que (/ˈsɛstwi ˈkeɪ/; also cestuy que, “cestui a que”) is an abbreviated version of cestui a que use le feoffment fuit fait, literally “The person for whose advantage the feoffment was made.” It is a French expression of the English medieval invention that is present in the legal sentences cestui que trust, cestui que use or cestui que vie. In contemporary English, the expression “setty-kay” (/ˈsɛtikeɪ/) or “sesty-kay” (/ˈsɛstike/). According to Roebuck, cestui que use “setticky yuce” (/ˌsɛtɨkiˈjuːs/).  Cestui que use and cestui que trust are more or less interchangeable terms.
In some medieval materials, the expression is considered a cestui a que. But later, after the Great Plague of 1665 and the Great Fire of 1666 destroyed London, the British government passed the Cestui Que Vie Act in 1666, which reintroduced the legal concept. After these two disasters, hundreds of thousands of British citizens died or fled. In response, the government took all private property into the trust until the good heirs or owners were identified – the cestui que vie. Parts of the 1666 Act are still law in the United Kingdom. If a fault had been made a fault by the use of cestui que and the defendant pleaded “nihil habuit tempore dimissions”, the applicant would have lost his appeal if he had not made a particular reply to the facts.  The aim of these changes was to make it more complicated and economically unattractive. When a position of trust is established, it is done in favor of a given person identified in the document of trust. In a trust, the cestui que trust is the person who has a fair interest in the trust.
However, the legal title of the trust is transferred to the agent. . . .