The key money paid for giving up

Q: My father (may Allah be merciful to him) rented an apartment in a house in the city of Kafr Al-Shaykh, in the Arab Republic of Egypt around 30 years ago, for a monthly rent according to a rental contract between the owner of the house and my father. Around ten years ago, Allah enabled my father to buy a piece of land in the same city on which he built four apartments for his four children. My father passed away a year ago and the owner of the house offered a sum of money to my adult siblings to leave the apartment. They agreed to do this and took the money from the owner of the house. When they told me about this, I told them that this was not permissible and it is Haram (prohibited), because we do not need the apartment or the money, so I asked them to return the money to the owner of the house. They promised to do so and one of my siblings did actually meet the owner of the house and agreed an appointment with him to return the money. (Part No. 15; Page No. 94) They told me that the owner of the house is a merchant and he offered money to the residents of two other apartments to leave the building, because their rent is very low. He wants to make an investment from this building by taking deposits and increasing the rent by 50%. One of my brothers is asking: Is it permissible for us to donate this money to one of the Islamic projects or charities, knowing that Allah is Good and only accepts that which is good, and that we will not get Thawab (reward from Allah) for it? My brother also says that the owner of the house is the one who offered this money to the residents and we did not encourage him to do so. The question for which we would now like a Fatwa (legal opinion issued by a qualified Muslim scholar) from Your Eminences, is: Is it permissible to donate this money to one of the Islamic charitable projects and not give it back to the owner of the house? May Allah reward you with the best.