Is it permissible to transfer the designated Sadaqah Jariyah amount to a different association, built by the heirs with their own money, when it was originally bequeathed to a specific association for the memorization of the Qur'an?

It is not permissible to change a will or divert it to a different entity than the one stipulated by the testator, for Allah Almighty says: ﴿But whoever alters it after he has heard it – the sin is only upon those who alter it. Indeed, Allah is Hearing and Knowing.﴾ The heirs must execute their father's will and disburse it to the association he specified, as long as it exists. Building an association for memorizing the Quran from the father's inheritance as an ongoing charity for him is good for them and for him if they are in agreement and are of sound mind, but this is not permissible if it is from a will designated for a specific entity.