Should terminally ill relatives and their families be informed of their hopeless medical condition to avoid further spending on futile treatment and to urge them to prepare for death, or should one remain silent hoping for a miracle?

Life spans are in the hands of Allah alone, and the doctors' words are based on conjecture, so their predictions should not be asserted as definite. Do not make your uncle despair of his life, nor prevent good from him. If you fear that he will be affected by being informed of the truth of his illness, then do not tell him, for the Prophet encouraged giving good tidings and forbade alienating people. Motivating your uncle to prepare for death is done through good advice and reminding him of Allah, the Hereafter, and the making of a will. What your uncle owns is his property, and he has the right to spend all of it on his treatment. The heirs' right to it does not become effective until after his death.