FORM help

I have figured out how to initially create multiple form documents. When I created the new forms in the MDI, I simply used OnFileNew() to create separate instances of that form. What I need to know now is how those different forms are indexed so that each one can be carrying out a different function than the others.

For example, my program will eventually be controlling four sensors through an A/D converter, all of which will need this same form, but if I want to control each sensor separately, I need to know how each form is indexed so that if I want to turn one sensor on, while the others stay off, I can do this.

Thanks for any suggestions
Dr_Confused