Yes your form will have to be dynamic ....you can use the presence property of the page and all children of the Page object will be affected. If you change the presence to invisible then the objects still exist in that they take up space but they cannot be seen. If you make it hidden then they do not take up space .....I believe that you will want hidden.
myform.myitem.presence = "hidden" didnt work, tried already and also tried many combinations of Page, form, subform, pageset hidden but none of them worked so far.
The solution would be a dynamic form but im working with static ones so i cant go deeper into it.
You could simulate dynamic form capabilities in static interactive forms, but it would require round-tripping back to the LiveCycle Forms Service server-side, and regenerating the PDF Form with the new layout.