Wanderers, Outcasts, Exiles: Half-elf Bard Social Graces?

Torchbearer An Adventurer's Essentials
1

I understand half-elves can choose Boasting or Singing. Is Merrymaking considered a Social Grace and can they choose this as a Nature Descriptor?

2

The Social Graces are Haggler, Manipulator, Orator and Persuader. Mention of merrymaking Nature in the musical instrument’s description is for the benefit of halfling characters.