I think what kari_dawn was suggesting was that you allow your broody hen to raise your EE chicks for you after they arrive. Many broodies will accept chicks if you slip them under her at night after she has already been sitting around 3 weeks. So if your EE chicks are due to arrive in the first part of April, you might consider slipping them under her the night after they arrive and see if she will accept and raise them for you - that way you don't have to worry about having a brooder in the house at all.
what HEChicken said! Sorry if I was being unclear! I get ahead of myself sometimes...conversations make sense in my head, and everyone else in the room is looking at me like "what?" *deer in the headlights* lol
First off, if she is an ISA Brown, she
may not be broody. Most more modern crosses have had broodiness bred out of them in favor of massive egg production. If she is a hatchery RIR or New Hampshire Red, there is a good chance she is broody. Another thing to consider is that you do not yet know how determined she is to set. I had an OEG that went broody, four months later, she was still sitting on nothing and looking rather frazzled, loosing weight by the day, and not even cose to giving up; so I gave in and gave her some feed store babies. She was a phenominal mother. It really depends on the hen.
Changing her eggs for dummies may be a good test to see how determined she is. I would change them simply because if the eggs are duds from all the meds, at least if you replace them with dummies, they can't rot and break under her (EEEW!). If you break her from being broody just from that, there is a good chance she wasn't determined enough to hatch.
You can take some hardware cloth or other wire mesh and roll some around her to make a kind of pen to keep her separate too...as for the others, put another dummy egg back in the milk crate and see if you can convince them to start laying in there again.
I gave Bonnie her chicks in the middle of the day on a weekend so I could watch how she interacted with them. At first, I tried to move her and the new crew into a dog crate, but she would have none of it and tried to keep the babies away from her. Once I put her back in the favorite nest, and gave her the kids, she became instant mommy. It was really darling. I recommend doing intros when you can supervise.