If you're looking for a way to switch voids on and off in a family, you can't. You can only move them out of the solid. You can mimic the 'switch on and off' effect using the following parameters and conditional statement:
D1 (Length) - This is an input parameter where you can enter the distance from the solid.
D2 (Length) - Forumla=if(VOIDCUT, 0 mm, D1) This is the parameter that you use in the label of the dimension from a ref plane to the void.
If the parameter 'VOIDCUT' is checked, then it will make D2 a value of 0. This means that the void object will be inside the solid, thus cutting it. But if 'VOIDCUT' is not checked then the value of D2 will be the same as D1.
Here's a video explanation...
Thanks to Patricks (Mask) for the sample family...