On February 8, 1934, Shoghi Effendi penned a work that would become the chapter titled "The Administrative Order" in his book World Order of Bahá'u'lláh, referring to "the deeds of its present and future Guardians" and noting "Divorced from the institution of the Guardianship the World Order of Bahá’u’lláh would be mutilated..."Divorced from the institution of the Guardianship the World Order of Bahá’u’lláh would be mutilated and permanently deprived of that hereditary principle which, as 'Abdu’l-Bahá has written, has been invariably upheld by the Law of God. “In all the Divine Dispensations,” He states, in a Tablet addressed to a follower of the Faith in Persia, “the eldest son hath been given extraordinary distinctions. Even the station of prophethood hath been his birthright.” Without such an institution the integrity of the Faith would be imperiled, and the stability of the entire fabric would be gravely endangered. Its prestige would suffer, the means required to enable it to take a long, an uninterrupted view over a series of generations would be completely lacking, and the necessary guidance to define the sphere of the legislative action of its elected representatives would be totally withdrawn.
Severed from the no less essential institution of the Universal House of Justice this same System of the Will of ‘Abdu’l-Bahá would be paralyzed in its action and would be powerless to fill in those gaps which the Author of the Kitáb-i-Aqdas has deliberately left in the body of His legislative and administrative ordinances.
“He is the Interpreter of the Word of God,” 'Abdu’l-Bahá, referring to the functions of the Guardian of the Faith, asserts, using in His Will the very term which He Himself had chosen when refuting the argument of the Covenant-breakers who had challenged His right to interpret the utterances of Bahá’u’lláh. “After him,” He adds, “will succeed the first-born of his lineal descendants.” “The mighty stronghold,” He further explains, “shall remain impregnable and safe through obedience to him who is the Guardian of the Cause of God.” “It is incumbent upon the members of the House of Justice, upon all the Aghsán, the Afnán, the Hands of the Cause of God, to show their obedience, submissiveness and subordination unto the Guardian of the Cause of God.”
Referring to both the Guardian and the Universal House of Justice we read these emphatic words: “The sacred and youthful Branch, the Guardian of the Cause of God, as well as the Universal House of Justice to be universally elected and established, are both under the care and protection of the Abhá Beauty, under the shelter and unerring guidance of the Exalted One (the Báb) (may my life be offered up for them both). Whatsoever they decide is of God.”
From these statements it is made indubitably clear and evident that the Guardian of the Faith has been made the Interpreter of the Word and that the Universal House of Justice has been invested with the function of legislating on matters not expressly revealed in the teachings. The interpretation of the Guardian, functioning within his own sphere, is as authoritative and binding as the enactments of the International House of Justice, whose exclusive right and prerogative is to pronounce upon and deliver the final judgment on such laws and ordinances as Bahá’u’lláh has not expressly revealed. Neither can, nor will ever, infringe upon the sacred and prescribed domain of the other. Neither will seek to curtail the specific and undoubted authority with which both have been divinely invested.
Though the Guardian of the Faith has been made the permanent head of so august a body he can never, even temporarily, assume the right of exclusive legislation. He cannot override the decision of the majority of his fellow-members, but is bound to insist upon a reconsideration by them of any enactment he conscientiously believes to conflict with the meaning and to depart from the spirit of Bahá’u’lláh’s revealed utterances. He interprets what has been specifically revealed, and cannot legislate except in his capacity as member of the Universal House of Justice. He is debarred from laying down independently the constitution that must govern the organized activities of his fellow-members, and from exercising his influence in a manner that would encroach upon the liberty of those whose sacred right is to elect the body of his collaborators.
It should be borne in mind that the institution of the Guardianship has been anticipated by ‘Abdu’l-Bahá in an allusion He made in a Tablet addressed, long before His own ascension, to three of His friends in Persia. To their question as to whether there would be any person to whom all the Bahá’ís would be called upon to turn after His ascension He made the following reply: “As to the question ye have asked me, know verily that this is a well-guarded secret. It is even as a gem concealed within its shell. That it will be revealed is predestined. The time will come when its light will appear, when its evidences will be made manifest, and its secrets unraveled.”
Vance Salisbury has chronicled a few of examples of Bahá'í books that have been edited after their authors' deaths...
John Ferraby served as the Secretary of the National Spiritual Assembly of the Bahá'ís of the British Isles and was appointed a Hand of the Cause of God in 1957. Later that year he authored All Things Made New. From 1959 to 1963, he served as one of the nine Custodians at the Baháʼí World Centre in Haifa, Israel. Comparing the original 1957 edition of All Things Made New to the 1987 edition, among the numerous alterations, is the replacement of his dedication of the book to "The First Guardian of the Baháʼí Faith" to simply "The Guardian." Other references to "the Guardian" have been replaced with "the Universal House of Justice."
George Townshend) was an Irish Anglican clergyman who became a Baháʼí and in 1947, at the age of 70, renounced his orders to the Anglican Church. Townshend was one of the founding members of the Dublin Local Spiritual Assembly and in 1951 was designated by Shoghi Effendi as a Hand of the Cause of God. Townshend completed his own book, Christ and Baháʼu'lláh, which Shoghi Effendi called 'his crowning achievement' shortly before dying of Parkinson's disease in 1957, at the age of 81. Christ and Baháʼu'lláh is notable for the changes made from the original publication to subsequent editions published after the passing of Shoghi Effendi. For example, a statement about the "first and present Guardian" has been removed and a section discussing "the lineage of succeeding Guardians" has been replaced with a section discussing "divinely guided institutions" in general.
The original edition of Shoghi Effendi's The Selected Writings of Shoghi Effendi, published in 1942, included numerous references to the institution of the Guardianship and its inspired origin, its perpetual nature, and its absolute centrality to the Covenant. This collection of his writings opened with a large extract from the Will and Testament of Abdu'l-Bahá which could best be summed up as an appeal to the believers to be "firm in the Covenant" and follow the divine guidance which can only be found in the Cause of God. In the 1975 edition, most of the text of this appeal has been removed, except for two paragraphs which promised that the Twin Pillars of the Guardianship and the Universal House of Justice are under the guidance and protection of Bahá'u'lláh and the Bab. However, the phrase "...and after him will succeed the first-born of his lineal descendants" no longer appears at the end of the paragraph concerning the Guardian. Two complete pages have been removed from the original edition without notation, including this explicit statement:
Divorced from the institution of the Guardianship the World Order of Bahá'u'lláh would be mutilated and permanently deprived of that hereditary principle which, as Abdu'l-Bahá has written, has been invariably upheld by the Law of God. 'In all Divine Dispensations,' He states, in a Tablet addressed to a follower of the Faith in Persia, 'the eldest son hath been given extraordinary distinctions. Even the station of prophet hood hath been his birthright.' Without such an institution the integrity of the Faith would be imperilled, and the stability of the entire fabric would be gravely endangered. (78)
Source : https://www.reddit.com/r/exbahai/comments/isnq3v/in_the_future_when_the_next_manifestation_appears/