I’m no expert, and CT can obviously give better information, but quad strength is very rarely the issue with a squat turning into a good morning; usually, the issue lies in the inability of the posterior chain to produce equal force to the anterior. Partial action of the quads is to extend the knee, while partial action of the posterior chain (in this case, glutes and hams) is to extend the hips. Without the glutes and hams extending with equal force to the quads extending the knee, the hips rise faster - but don’t extend - and lead to you dropping forward.
Goblet squats are still a great initial squat for someone who has never lifted, but once she starts using a barbell, hip extension and strength will need to be remembered. A common cue is “chest up”.