Nothing in this Act shall be construed as preventing a patient who requires treatment for mental disorder from being admitted to any hospital or mental nursing home in pursuance of arrangements made in that behalf and without any application, order or direction rendering him liable to be detained under this Act, or from remaining in any hospital or mental nursing home in pursuance of such arrangements after he has ceased to be so liable to be detained.

In the case of a minor who has attained the age of 16 years and is capable of expressing his own wishes, any such arrangements as are mentioned in subsection (1) above may be made, carried out and determined notwithstanding any right of custody or control vested by law in his parent or guardian.