Billboard 18 Month Rule
Any new mix of a song released after 18 months of the original version is treated as a new song and is not rolled-up/merged into the original version..
If the new mix is released less than 18 months from the original version, the original version needs to still be current on Billboard Airplay charts. If the original version is re-current that new mix is tracked separately.
No live versions of a song can be released within the 1st 4 weeks of the original versions release.