Personally, I would do it a little different. I'm assuming you don't want there to be an extra beat or two added in, so what I would do is copy the sequence that's right before the drop (the one that you need to have a drop at the end of). On the copy, do the drop... edit out notes in each track using step edit, or you can use the erase button, or you can use SEQ EDIT. Then, insert the sequence that has the drop at the end of it wherever you need it. That way, you still have the full version of the sequence if you need it, or you also have the same exact sequence except with a drop in it.