both have been using weight machines without incident but would like to change up their routine but every time I try to incorporate a new free weigh lower body exercise they don’t want to do it for fear it will hurt their knees. They are doing the leg press, leg curl, leg extension machines now and have no problems. Are there lower body free weight exercises that do not include, squats, lunges, steps???
the key phrase here that your clients are afraid, and you simply have to honor this fear, you cannot talk it away.
One thing to point out to them is that life is a series of free weight exercises. Toilet? Looks like a squat me. Picking something up from the floor? Can’t do it without a lunge. They are already doing free weight exercises but may not think about it in those terms.
Try to make those exercises relevant to them and start with ranges of motion in which they can be successful. Overcoming the fear is the main part here. Once they have a little success they will be willing to try just a bit more.
I wish you (and them) good luck.