Minecraft Teleport Command with radius?

I hope someone can help me. I want to build a teleport system in minecraft 1.8.9. People should be sent to a location via a command block. But: I want only people in a certain area to be teleported. And they should not all be on one block, but in the same "formation" as before. So everyone should stand as they were before teleporting. Can someone write me the command? And is that only with the radius or even with the area between 2 coordinates?

Unfortunately, I do not know exactly how to teleport them in the same formation but in the radius it works like this / tp @a [r = *] ~ ~ ~

Maybe I can help you, even if I did not quite understand your request. Would be cool if we could talk on TS or Discord about it.
If you are interested you can contact me.