What is the third dimension, the height? Pictures do help. Can you explain where and how you got your set up. Is this a boughten coop? Often times, those are sited as to hold a lot more chickens than they really can, so that might be part of the problem with your parents, they have been told that more can fit in there by the company. This happens often when new people want to get into chickens and buy a ready made coop.
However, you really do only have 3 options: cull birds, make the set up larger, or get sick and mean birds.
Some very nice work has been done with pallets, look around this site. Also, what part of the world is this? Some places chickens need much less protections, as in an open shed, with two or three walls and a roof is all. Personally, I like a coop/enclosed run set up. I let mine free-range, but they do fine in lock down too.
You are right, they are wishing it will all go well, time will prove it.
Mrs K