Some climbers prefer the ATC because the GriGri favors right-handed belayers. Others can't get over the idea of rappelling with a GriGri. But when it comes down to convenience and redundancy, the GriGri seems to take the cake.

A bottom belay is possible for beginners rappelling with a GRIGRI (as with many other descenders): pulling on the rope from below can slow or even stop the descent. The person performing this maneuver must pull by hand, without hanging on the rope.

gri·​gri. less common spelling of gris-gris. : a talisman, amulet, voodoo charm, spell, or incantation believed capable of warding off evil and bringing good luck to oneself or of bringing misfortune to another.

Daughter is using a Grigri as a self-belay device. This is expressly discouraged by Petzl, the manufacturer, on this page titled Self Belaying is Prohibited. That's pretty damning. As the page admits, some people do use a Grigri for self-belays, but it's not ideal and potentially dangerous.