Backplate to collar plate question

is the backplste attached to the collar armor? i think so just looking for confirmation.

Yes. The collar overlaps the back by about an inch.

You can use the collar studs to keep them attached. That's what I do.

I use two snaps, one inbetween the stud and backpiece. They overlap and it simulates that the studs are holding the two pieces of armour together, but they aren't.