What is the ruling on a son building an extension to his father’s house without prior agreement, and the father refusing to estimate the value of the construction to establish the son’s right, knowing that the other children are aware of the building and renovations?

Issues of inheritance and disputes cannot be resolved merely by asking from afar. Rather, they must be presented to Sharia courts or discussed directly with scholars to hear both parties. What has been mentioned is not sufficient for a definitive ruling. However, if you were not donating what you did, then the matter depends on agreement with the heirs. If they agree, there is no harm. Otherwise, the ruling belongs to the judge. But if you were donating, and then demanded it back, that is not permissible. Custom (urf) also has a bearing in such matters.