Becca, your big coop, the first one that was built, is large enough to house a good bit of your flock. It has plenty of space. Course, I'm not totally sure how many you have in there right now?
My main coop is around 9x10 after you take out walkway space. I have considered 22-25 birds in there. Right now there are 22, and they are squabbling over roost space. I have a hen roosting on the window ledge (which will disappear when I put the window in for winter). I'd need to add another plank of roosting area and another couple nest boxes.
My back coop has two rooms that are 5x9. I might get 10 in each. Right now 10 hens and one turkey are sharing the roost in there just fine, but the floor space is very tight and I opened the door to let them roam the middle area of the building during these rains. That coop still has no nest boxes.
A thought!
If I take off the doors to the separate rooms in the back coop, I could have 2 rooms of 5x8 plus the middle area that is about 6x8 with dividing wall and upper shelf, I could set up one heated watering station and let the birds share the full area and 2 runs.
Now to figure out how to run power out there over the waterfowl yard.
I think I can combine flocks with these young roos, but Romeo would probably kill a new young roo just introduced to the flock. I haven't seen him flog one of his 2 sons yet, but those boys aren't allowed much food access. Those boys and 4 hens (and perhaps Romeo) are on my freezer list anyway.
Could you put all the portable pens into the detached garage?
Or tarp the portables together?
Move a portable into a fixed coop but keep the birds in the portable pen in their separate pen?
Tarping two big hoop houses together for shared body heat is a good idea (not really movable, though). I'm considering putting my turkeys in hoop houses, but I worry about old big tom with my young tom and babies.
I park in the outer garage during winter so I don't have to clean my car off every morning. #pout# But I could give up my car space to my chickens.
LOL
I have seriously considered using my flatbed trailer as a coop inside the garage this winter. Last winter I stored some pallets on it, but usually the trailer just sits inside all winter. I'd cover the floor with tarp and use a hoop system to cover the top. Could tarp it to hold heat in a round the birds. Rigging a "door" for my access might be tricky, but not impossible.
No outside time for those birds, but might be a good place for the Polish, Salmon Favorelle, and Amerucana that are still in brooders now.
Water still freezes in the garage, but power is much more accessible. Garage has an old heater, but we can't make it work.
Even if it is raining. 
