I'm certainly no expert in the subject - but can offer this tidbit of info.
If your newbies are the same color/size they will notice less.
If the newbies are really different - they will be more noticeable.
I also changed the food & water dishes so they all went out together to a new breakfast...
Be prepared to feed wild birds and rodents
(mice/rats/chipmunks/squirrels/groundhogs)
unless you use 100% hardware cloth up down underneath and around!
(so happy that our coop & run is Fort Knox)