Is it permissible for me to take an additional quantity of milk without the knowledge of the farm owner, knowing that the excess quantity will be discarded the next day, and is this permissible for others who are not allocated milk?

It is not permissible to take any milk without the permission of the farm owner, due to the Prophet's (peace be upon him) saying: "Every Muslim's blood, wealth, and honor are sacred to another Muslim." The farm owner should be alerted that the milk will spoil if it is not utilized, and that if he permits others to benefit from it, he will be rewarded for that. It is expected that he will permit the use of what is not suitable for marketing.