Once the turkey legs have simmered for 10 minutes, add the greens, salt, and sugar, reduce the heat to low, cover, and allow to simmer gently until the greens are tender, about 45 minutes, stirring the greens every 10 to 15 minutes. Taste and season with additional salt, if desired. Remove the turkey legs and save for another use or shred into the greens, if desired. Serve immediately.