Not necessarily going to be too much of a difference in PAT from yours. They still might be able to get one close to yours or exactly at yours. And as you know the PAT is tied to your Boarding group number, so they might end up being with you that way as well.
However, if this does not work when they do their on line check in, you could ask the CM if they could board with you, and if not then wait for them so you can board together.
It really is the discretion of the CM.