What should I do about my friend's dish, as she has traveled, and is it permissible for me to estimate its value and donate the amount? And what should I do about the dish that does not belong to me, which was left by the previous building superintendent, knowing that I do not know its owner, and is it permissible for me to use this dish?

You must search for the aforementioned sister and contact her to inform her about her dish and dispose of it according to her request. If you do not find her, you should dispose of it according to the rules of lost property (Luqata). As for the utensils and dishes found at your doorstep whose owner you do not know, ask your neighbors. If you do not find their owners, then if they are trivial and worthless, you may take them and use them or donate them. However, if they are valuable, keep them and publicize them for a year. If their owner comes, hand them over to him; otherwise, use them or donate their value on their behalf. If their owners come afterward and do not approve the charity, you must compensate them. Your use of the dishes before the mentioned period is permissible if they are trivial; otherwise, it is a mistake that requires seeking forgiveness.