I'm going to jump out a window if I hear more quad settings stuff from MD's. They don't work. It's like walking around in your old 70's leisure suit (yeah, I had a few).
Get these athletes step-uping, squatting, and lunging as soon as possible. It's easy if you understand TWEAKOLOGY. That is, using UE or LE drivers to help the knees out. Where they have the pain (ie medially, laterally, inferiorly) will guide you on where to go. Here are some good places to start.
1. RLE stagger squat. You might think this is more difficult than a traditional squat. However, there is practically 0 knee excursion going on and is usually more comfortable. In addition, you are recruiting more hamstring, which in this position is a knee extensor, assisting the quads.
2. SLS c/ BUE same side rotation @ shoulder height. Recruiting more glute in the TP- again assisting the quads.
3. SLS c/ BUE @ shoulder height anterior reach to max; this time recruiting more glute & erector spinae in the SP, again assisting the quads.
Of course as the athlete gets stronger, you will need to tweak the quads back in. Topic for a future post.