In part, what XLD is referring to here is that just because something CAN be done does not necessarily mean that it SHOULD be done as a matter of course or that it is the best option.

The course that Steve has alluded to would be the better option... You can have almost any number of controls on a form, just set their visible property to false until the conditions are met where you want them shown.

Another alternative would be for the extra controls to be (say) added onto the RHS of a form of width 2 * X, and when the form is activated set the form width as either X, or, 2 * X if your conditions to show the extra controls are met. Or maybe you'd want to show it as width X, and set the width as 2 * X when (say) a button is clicked...