The cover of smash-hit Jolene, with Welsh and English lyrics, is released on Friday.
Parton's niece Jada Star and Welsh singer Bronwen Lewis say the country artist was proud to sing in Welsh.
The Grammy-winning US country music star, 45, says he currently feels "great" and is "hopeful".
The day is observed on 25 September, or 9/25, as a nod to the late Queen of Country's hit song 9 to 5.
Bryan Seaver, who announced Parton's death to the world, is accused of trying to extort her estate.
Kelly O'Brien says she will carry on performing as Dolly Parton after the singer's death.
Dolly Parton's estate says DollyFest will take the place of a traditional public memorial for the artist, just as she wanted.
A private family funeral is held for the singer who died on Tuesday at the age of 80.
While country music and films brought her fame, her entrepreneurial zeal brought her fortune.
