Did Swami move beyond the charter of 1981?

Yes. Swami changed the charter as the times changed as He knows what is best. He directly gave the SSSIO senior leadership instructions.  Swami changed many items and created the Prasanthi Council and approved the different zones of the SSSIO. Swami also created the Sri Sathya Sai World Foundation. Swami approved the bylaws of the SSSIO and the officers He appointed have a lifetime term.

Obeying My instructions is enough; for it will benefit you more than the most rigorous asceticism.

Practise Sathya (truth), Dharma (righteousness), Santhi (peace), and Prema (love), which are dear to Me. Resolve to keep those ideals before you, ever in all your thoughts, words, and deeds. That can confer on you the summum bonum of mergence in the Supreme Substance of Divinity.

Sri Sathya Sai Baba, May 17, 1968