In the 1970s, most if not all Joplin compositons still were within the 75-
year limit and theoretically protected by copyright law.  The "descendant"
of the composer or the composer's trust would still be a negotiable organ
for anyone planning a recording today of music copyrighted after 1922.

An example is Patricia Lamb, the daughter of ragtime composer Joseph Lamb.
Patricia is still quite alive last time I heard, and very flattered by
anyone interested enough in her father's music to want to record it.
(She's less interested in money and more in her father's reputation and
legacy).  In fact, I heard an excellent arrangement of Lamb's "American
Beauty Rag" arranged by David Wasson for the Mills Violano.

Cheers, S. K. Goodman