Possible to add BOGO on my current 4 line that has 3rd line free

Is it Possible to add BOGO on my current 4 line that has 3rd line free on Experience Beyond 1.0. Then later remove the 4th line that i am paying and still keep the 3rd line free and the new 2 BOGO lines? On top of that my 4th line i have a free phone they are crediting is that able to be moved to the new BOGO?