An open mind is a prerequisite. Make this known. Tell them they are here to learn what you consider are the best techniques. If they feel otherwise, they can revert to what they were doing when they leave and make a judgement on whether they want to return. In your dojo, it's your way.
Just like with shooting, i teach an isosceles stance. Even if you have always used the weaver stance, when you train with me you use isosceles. When you leave, you can judge for yourself whether you want to keep using it or go back to a weaver stance.