Here in 2 Nephi 2:22, the printer’s manuscript has the relative clause “which they were”, which seems incomplete. The original manuscript is not extant here, but the in could have been accidentally lost when Oliver Cowdery copied from 𝓞 into 𝓟. We do have an example elsewhere in the text where in occurs both at the head of a relative clause and at the beginning of a preceding prepositional phrase:
The editing of 2 Nephi 2:22 for the 1920 LDS edition is therefore consistent with the language in Helaman 5:21.
Another editing possibility would be to add the in to the end of the relative clause, so the text in 2 Nephi 2:22 would read “all things ... must have remained in the same state which they were in”. There is some evidence to support this second possibility. First, in two other places the Book of Mormon text has the word state followed by a relative clause where the relative pronoun which directly follows a prepositional phrase. In both instances, the required preposition comes after the verb in the relative clause, not before the which:
The first of these two examples suggests that whenever the relative clause means ‘to be in some place or state’, the in comes at the end of the relative clause after the be verb. Here is one other example:
In four cases, the preposition in occurs redundantly, both at the beginning and at the end of the relative clause. All four relative clauses have whatsoever as the relative pronoun and refer to geographical place:
In the first and fourth cases, the text has retained the redundancy. In the second case, it seems that Oliver Cowdery accidentally dropped the redundant in as he copied the text from 𝓞 into 𝓟, probably because the immediately following text also began with an in (“in any part of their land”). Note in Alma 34:38 that Oliver was able to keep all the in’s (“in whatsoever place ye may be in / in spirit and in truth”). Finally, in the third case, the 1840 edition removed the preposition at the beginning of the relative clause, thus leaving the preposition at the end. The 1908 RLDS text restored the first in. On the other hand, the 1920 LDS edition removed it (perhaps by reference to the 1840 edition); the deletion is explicitly marked in the committee copy for the 1920 edition.
All of these examples show that the original text never allowed the main verb be to end a relative clause with the meaning ‘to be in some place or state’. Perhaps there is something too abrupt about the ending of a relative clause like “in which they were”. And in four cases the preposition in occurred at the end even when it had already occurred at the beginning of the relative clause. We should note that in most of these cases there seems to be no attempt to follow the prescriptive grammatical rule of never ending a sentence or clause with a preposition. The Book of Mormon text is full of such examples (including those listed above). This artificial rule is absolutely incorrect for the English language. (For a thorough discussion, see preposition at end in Merriam-Webster’s Dictionary of English Usage.)
Thus in 2 Nephi 2:22 the earliest reading (“in the same state which they were”) definitely sounds inappropriate. Based on usage elsewhere in the text, the preposition in should occur at the end of this relative clause rather than at the beginning.
Summary: Emend 2 Nephi 2:22 so that the relative clause ends in the preposition in (“which they were in”); examples elsewhere in the earliest text argue that relative clauses with the meaning ‘to be in some place or state’ never end with the main verb be.