Ahhhh ok So cutting this short. This might explain...
When a Copyright Owner dies, the copyright (which is good for 70 years) is then transferred to whomever is specified in the Owner's Will. Which in James L Mack's case, was HM. So I did a search at the Copyright Office.... Check this out.
http://cocatalog.loc.gov/cgi-bin/Pw...HUo20Elefv73&SEQ=20150413154634&CNT=25&HIST=1
Some are co-owned, others were filed by Employers/Labels etc. Some are a different James Mack. Now, there was an article I saw back when SWM was having an Estate Sale, and someone had purchased as many JMs original music compositions as she could (?). Some of which may have already been filed with the copyright office.