Leg Day Question (Knee pain)

We really need more information here. When does it hurt? During flexion or extension? What exercise is she doing when it hurts and at what point in the motion does it bother her? Both upper and lower at the exact same time?

There is no universal standard for "form" on complex moves like a squat in particular where targeted depth should be derived from things like bone length and flexibility. Are you a CPT? If you are, you should know this.

Get you some knee sleeves.

Rehbands are a pretty good brand. Keeps your knees supported and comfortable.