Adding/Removing a scriptUI Group

Here's my code:

dropSelec.onChange = function secOff()
        {
            if (dropSelec.selection==3)
            {
                if (offGroupMain.children.length==1)
                {
                var offGroupT=offGroupMain.add("group");
                var secOffOne = offGroupT.add ("statictext", undefined, "Offset Two:");
                var secOffTwo = offGroupT.add ("edittext");
                secOffTwo.characters = 5;
                secOffTwo.text="1";
                var secOffThree = offGroupT.add ("statictext", undefined, "frames");
                win.layout.layout(true);  
                }
             }
         if (dropSelec.selection!==3)
         {
            if (offGroupMain.children.length>1)
            {
             offGroupMain.remove(offGroupT);
             win.layout.layout(true); 
             }
          }
         }

I'm trying to make it so that when my drop down menu is on a certain selection, it creates a new line in the UI, and removes it when changed to anything else.

Right now it is both adding and removing the line when I switch to the specified selection.