My current emergency plan is, I would put all 7 chickens into a large dog crate and bring them in the house.
If you bring them inside for very many days, they will start to get used to the warmer temperatures in the house, and they will have more trouble when you put them back in the coop again.
Our temperatures last winter went down to -36*F, and not just for a short time either.
Have you measured the temperature inside the chicken area? It is probably several degrees warmer than outside, even with no heat at all. And of course you would never have to worry about wind chill if the chickens are out of the wind.
If you do bring them somewhere "warm" during a power outage, I think you should not bring them anywhere warmer than about 35 degrees (Fahrenheit), and it might be better if you kept them closer to 0. That way there is not much shock from coming into the warmth and later going back out into the cold.
The chickens needed their heat lamps on quite a bit.
How warm were you trying to keep them?
We don’t have a generator. We have a wood stove in the house.
You should be able to heat water if you need to.
So you can make sure they have enough liquid water to drink, and you can also make them a warm mash (just add warm or hot water to a dish of their normal chicken food, then make sure it isn't hot enough to burn them.) That should encourage them to eat more than usual, so they will have the calories they need to help keep themselves warm.
My current emergency plan is, I would put all 7 chickens into a large dog crate and bring them in the house. Just wondering for how long they would be ok to be crammed in a small space together.
Even if you feel the need to do this at night, I would probably put them back in their coop during the day. They can all huddle up and night and sleep, but daytime is when they need space to move around. Moving around also generates heat, so that helps keep them warmer, and of course daytime also tends to be warmer than nighttime.
Even putting them in the coop for half of each day (afternoon) would be better than keeping them crowded all day long, but I think putting them outside all day would be better yet.
Does their coop have natural light? Glass windows can be a great thing in northern areas in the winter. (They also need ventilation, and some light usually comes in through any form of ventilation, but windows are great for letting in a lot more light.)