You have been unable to provide any proof that Taney so much as knew John Merryman.
Chief Justice Taney was resident in Washington, D.C. with no residence in Maryland. Merryman was resident in Maryland. Presumably they were neighbors in MD and DC together. Perhaps the alleged friendship arose from going to different schools together.
Chief Justice Taney sold his home in Maryland in 1855 and moved to Washington, D.C. More specifically, he was living at 23 Blogden's Row, on Indiana Avenue, near the Court House. See Carl Brent Swisher, Roger B. Taney, pp. 471 and 472.
http://www.geocities.com/doswind/myers/supreme_11.html
According further to Tyler, Taney was poor. In an interview with Tyler, published after Taneys death in the Cincinnati Commercial newspaper, Tyler was asked : Was Judge Taney rich, Mr. Tyler? No, sir, replied Tyler, always poor. He lived in Blagden row -- the row of stuccoed houses opposite the City Hall. They are four-storied; an iron balcony runs above the first story; two windows adjoin the hall door."
I provided the passage from the New York Times, as quoted by Rehnquist. To date, it stands unrefuted.