For something to be officially added to or removed from the Canon requires a vote by the governing body of the church. That would be either the First Presidency or the Quorum of the Apostles. Historically these two groups of equal power have never been at odds about anything.

Behold, I would exhort you that when ye shall read these things, if it be wisdom in God that ye should read them, that ye would remember how merciful the Lord hath been unto the children of men, from the creation of Adam even down until the time that ye shall receive these things, and ponder it in your chearts.

And when ye shall receive these things, I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost.

And by the power of the Holy Ghost ye may know the truth of all things. - Moro. 10:3-5

1 Verily, thus saith the Lord unto you concerning the Apocrypha--There are many things contained therein that are true, and it is mostly translated correctly;

2 There are many things contained therein that are not true, which are interpolations by the hands of men.

3 Verily, I say unto you, that it is not needful that the Apocrypha should be translated.

4 Therefore, whoso readeth it, let him understand, for the Spirit manifesteth truth;

5 And whoso is enlightened by the Spirit shall obtain benefit therefrom;

6 And whoso receiveth not by the Spirit, cannot be benefited. Therefore it is not needful that it should be translated. Amen.

A few weeks ago in Sunday School, a sister stated that General Conference talks are scripture. Being the teacher, I challenged her to find something to back that up.

She did a lot of research and found that, although there are supporting statements from the brethren, there isn't anything which explicitly states that General Conference talks are scripture.

In D&C 68:4 it says that when the Lord's servants speak by the power of the Holy Ghost, what they speak is scripture.

There may be lots of talks and articles that fall into this category, but doesn't claiming that all of GC addresses are, and always will be, scripture impose on the agency of the speaker?

I know that the four Standard Works are canonized, but I haven't hear about anything else being added to the list.

"When Are the Writings and Sermons of Church Leaders Entitled to the Claim of Being Scripture?

I assume the scripture behind this question is the declaration of the Lord in a revelation given through Joseph primarily to Orson Hyde, Luke S. Johnson, Lyman E. Johnson, and William E. M'Lellin, who were to engage in missionary work. After addressing a word first to Orson Hyde, the Lord continued:

"And, behold, and lo, this is an ensample unto all those who were ordained unto this priesthood, whose mission is appointed unto them to go forth-- And this is the ensample unto them, that they shall speak as they are moved upon by the Holy Ghost. And whatsoever they shall speak when moved upon by the Holy Ghost shall be scripture, shall be the will of the Lord, shall be the mind of the Lord, shall be the word of the Lord, shall be the voice of the Lord, and the power of God unto salvation. (D&C 68:2-4.)

The very words of the revelation recognize that the Brethren may speak when they are not "moved upon by the Holy Ghost"; yet only when they do speak as "moved upon" is what they say considered scripture. No exceptions are given to this rule or principle. It is universal in its application.

The question is, how shall we know when the things they have spoken were said as they were "moved upon by the Holy Ghost"?

I have given some thought to this question, and the answer thereto, so far as I can determine, is: We can tell when the speakers are "moved upon by the Holy Ghost" only when we, ourselves, are "moved upon by the Holy Ghost." In a way, this completely shifts the responsibility from them to us to determine when they so speak." President J. Reuben Clark

"And now I, Nephi, cannot write all the things which were taught among my people; neither am I mighty in writing, like unto speaking; for when a man speaketh by the power of the Holy Ghost the power of the Holy Ghost carrieth it unto the hearts of the children of men." - 2 Nephi 33:1

"This whole revelation (D&C 50) should be read with great care. There is much instruction given in it. But I wish particularly to call you attention to verses 21 and 22, just quoted:

"Therefore, why is it that ye cannot understand and know, that he that receiveth the word by the Spirit of truth receiveth it as it is preached by the Spirit of truth? Wherefore, he that preacheth and he that receiveth, understand one another, and both are edified and rejoice together."

Both are "moved upon by the Holy Ghost." ." President J. Reuben Clark

"And if there be faults they be the faults of a man. But behold, we know no fault; nevertheless God knoweth all things; therefore, he that condemneth, let him be aware lest he shall be in danger of hell fire." - Mormon 8:17

"What I the Lord have spoken, I have spoken, and I excuse not myself; and though the heavens and the earth pass away, my word shall not pass away, but shall all be fulfilled, whether by mine own voice or by the voice of my servants, it is the same.

For behold, and lo, the Lord is God, and the Spirit beareth record, and the record is true, and the truth abideth forever and ever. Amen." D&C 1:38-39

"And whatsoever they shall speak when moved upon by the Holy Ghost shall be scripture, shall be the will of the Lord, shall be the mind of the Lord, shall be the word of the Lord, shall be the voice of the Lord, and the power of God unto salvation.

Behold, this is the promise of the Lord unto you, O ye my servants." D&C 68:4

Further, I would encourage you brethren of the Aaronic Priesthood to receive a patriarchal blessing. Study it carefully and regard it as personal scripture to you--for that is what it is. A patriarchal blessing is the inspired and prophetic statement of your life's mission together with blessings, cautions, and admonitions as the patriarch may be prompted to give. Young men, receive your patriarchal blessing under the influence of fasting and prayer, and then read it regularly that you may know God's will for you.

Please keep in mind, not everything in the Quad is canonized scripture.
- Dragon

Now that the ruler has been established, and once you firmly grasp the meaning and content of the entire standard works, there are other resources which will provide a spiritually minded person with greater insights. These include, but are not limited to:
Hymns
General Conference Talks
Blessings given or received
Apocryphal writings
Stake Conference talks
Talks in Sacrament Meeting
Manuals for teaching
Chapter Headings in the Standard Works (not considered canonized scripture, but included for convenience only)
The Bible Dictionary (not considered canonized scripture, but included for convenience only)
Books published by church members or church leaders
Things your seminary teacher said
Joseph Smith Translation of the Bible
Other study guides included in the footnotes of the standard works (such as alternate Hebrew or Greek translations of words)

... is not intended as an official or revealed endorsement by the Church of the doctrinal, historical, cultural, and other matters set forth.

The chapter headings were written by Bruce R. McConkie and included in the 1979 printing of the LDS format of the KJV. To my knowledge, there was never a vote to accept or deny these chapter headings or other footnotes and maps as canon.

verses 24, Authoritative baptism is required.

2 Wherefore, although a man should be baptized an hundred times it availeth him nothing, for you cannot enter in at the strait gate by the law of Moses, neither by your dead works.

3 For it is because of your dead works that I have caused this last covenant and this church to be built up unto me, even as in days of old.

Therefore, he took Moses out of their midst, and the Holy Priesthood also;
26 And the lesser priesthood continued, which priesthood holdeth the key of the ministering of angels and the preparatory gospel;
27 Which gospel is the gospel of repentance and of baptism, and the remission of sins, and the law of carnal commandments, which the Lord in his wrath caused to continue with the house of Aaron among the children of Israel until John, whom God raised up, being filled with the Holy Ghost from his mother's womb.

Further more, the JST excerpts in the back have no more backing to them than the rest of the footnotes. If the JST were canon, we would read the JST Bible, and not the KJV.

The Book of Mormon was published in 1830, and no additions or changes have been canonized since then, other than those which are intended to correct spelling, punctuation, or grammar

The church has made statements that the corrections made are an attempt to bring the text as close as possible to what Joseph Smith actually translated. Missing phrases added back in is understandable.
However,I am a bit disturbed by changing white to pure. I can understand why the church leadership found it necessary. I know the church is led by men, and not by angels. I debated awhile back in my scripture study about using the paragraph markings and unifying the verses back together. Based on these comments, I think I will, especially because I have already read them in their current form, and perhaps it will give me new insights.

- Dragon

My opinion though on the original post - "What Books Should be Studied as Scripture?", is that any book or writing that testifies of truth and is supported by the Spirit can be considered scripture. But that may be different for everyone - as the Spirit testifies of different truths to everyone, at different times, and when they are ready to receive them. For example, my mother believes that Apocryphal writings are garbage because of a quote by Joseph Smith and that we SHOULD NOT read them (because they can "lead us astray....", etc...). So if she were to read them, she may not get anything out of them, and they certainly would not be scriptural for her. I have read a lot from Apocryphal writings and have had the spirit testify of some amazing truths and nuggets I've come across that helped piece together other things I was studying... so I believe that those things could be considered scripture FOR ME. Even with the canonized scriptures - as has been discussed, we still need to Spirit to testify of the truthfulness and accuracy of those, and to validate or correct our understanding, and to discern which things are not accurate or not sending the message that was intended.

4 And whatsoever they shall speak when moved upon by the Holy Ghost shall be scripture, shall be the will of the Lord, shall be the mind of the Lord, shall be the word of the Lord, shall be the voice of the Lord, and the power of God unto salvation.