Do you mean "Sanford" rather than Emerson? If so, Ferhenbacher discusses the problem on Pg 247-249 of his book.
In short, the link is that Mrs. John Emerson was formerly Eliza Irene Sanford. One of the Scott daughters is named after her. Mrs. Emerson inherited his late husband's estate in late 1843 and her brother, John F. A. Sanford was the executor. Mr. Sanford had failed to file a final report on the estate when he died in 1848.
Fehrenbacher later notes (pg 270):
"If Dred Scott v Emerson had been reviewed by the United Stees Supreme court, there would have been no Dred Scott v Sandford (sic), which was simply the alternative way of getting the case before that same Supreme Court. The crucial differnece was that the two major issues in the Sandford case - Negro citizenship and the contitutionality of the Missouri compromise restriction - did not appear on the face of the record in the Emerson case and would have been beyond the scope of federal court review. Thus a Supreme court decision in Dred Scott v Emerson would have been narrowly based and comparatively uncontroversial. In that event, unless Taney had been able to find another peg on which to hang his sweeping and inflammatory opinion of 1857, the great consequences attributed to the Dred Scott decision wouold have been unknown to history."
[cr #387] Ferhenbacher discusses the problem on Pg 247-249 of his book.
At page 272, Fehrenbacher writes the following:
First, no bill of sale or any other legal record of the alleged transaction between Mrs. Chaffee and her brother has ever been found. This does not mean however, that such a document never existed, and besides, a transfer of slaves, unlike one of real property, could have been as informal as the principals desired. In sum, the lack of documentary proof falls short of constituting disproof. The second consideration probably carries more weight. Sanford died on May 5, 1857, two months after the Supreme Court decision in his favor, and his probate papers contain no mention of the Scotts. Moreover, just three weeks later, Dred and his family were manumitted by Taylor Blow, who had recently acquired them from the Chaffees. Thus, if Sanford owned the Scotts in 1853, he must have returned them to his sister at some time before his death in 1857. [13] Again, there is no record of such a transfer, which, again, may have been made informally, but two unrecorded transactions do tend to stretch belief. The facts therefore discourage certitude. Sanford may have owned the Scotts as he said; there is reason to suspect, but no evidence to prove, that he did not. [14]---------------------------------
[13] Walter Ehrlich, "Was the Dred Scott Case Valid?"/AH, LV (1968), 263, maintains that such a transfer "could not have happened" because Sanford was confined in an insane asylum during the entire period from March 6, 1857, until his death on May 5 that same year. This assumes that Sanford would have had to continue as owner until the Supreme Court delivered its decision. However, the suit was an action of trespass for offenses allegedly committed on January 1, 1853, and the grounds for the suit (and for appealing the adverse verdict) presumably would have continued to exist if Sanford had sold Scott sometime before March 6, 1857.
[14] In "Was the Dred Scott Case Valid?" 262-63, Ehrlich points out that the Agreed Statement of Facts includes the egregious misstatement that it was John Emerson who sold Scott and his family to Sanford (Emerson, of course, had been dead since 1843). This may have been just a slip of the pen, or an effort to keep the facts simple, or a fiction employed to keep Mrs. Chaffee's name off the record. It adds to our doubt about Sanford's acknowledgment of ownership, but it proves nothing.
Source: Don E. Fehrenbacher, The Dred Scott Case, p. 272; footnotes p. 662.
Fehrenbacher seems to have a problem with Taney, but there were 6 other justices of a similar opinion. And again, the court continued the position held by the founders, framers, 1st Congress which limited citizenship to whites only, the second Congress, the third Congress ... Anybody see a pattern here?