Oh
@chanticleer I am so sorry. Meep is gorgeous. Never fails I'm afraid.
I lost a little rooster just a bit over two years of age 10 days ago. Completely blindsided me. I found him drooping on a roost bar, hopping around a bit but definitely sick. Got him down, skin and bones. No symptoms. Just wasted. I've been having problems, non-Marek's related with some of my cross bred hens that leads me to suspect something cardiac/genetic in nature but this little guy....I hatched him myself. Hand reared him. He was sweet and gentle and now I suspect that it is a Marek's loss after going almost 6 years without a suspicious death. I knew a big snow storm was heading in. I'd put him in a nesting box and he hadn't moved out of it in over 24 hours and was growing weaker. I put him down. It's heartbreaking especially when you are a second mom to them.
If you decide to cull your sweet hen, and can handle cutting her open, you will want to check her reproductive system. There are pictures on line that will tell you where everything is. It's not hard. Also check her liver. If there are tumors there you will see them. The one hen I necropsied had a huge infection in one of her ovaries. I found a large 3x2 inch hard ball of purulent matter on the ovary. It wasn't Marek's in her case. But given that Meep was having crop problems, you might want to make sure and take a look there as I did have a hen that wound up with what felt like a huge hard purulent ball in her crop when she died.
For the lameness to check for Marek's you will want to cut down in the inside of the thigh muscle, careful to dissect to the bone and look for the big sciatic nerve. Once again there are pictures on line. In MD the nerve will be greatly enlarged.
I'm so sorry. This won't be easy to do but you might have a better idea as to what is going on and what killed her if you can handle it. Be prepared though to not find anything that you can lay a finger on. It might happen.
I agree. There is much more than a broken wing going on. Two years ago my Little Joker, A SDW OEGB rooster I hand raised when his mother died turned up with a broken forewing. Really trashed the joint and it just crunched when I touched it. I tried to splint it and wrap it to his body but he would have nothing to do with it. So I kept him in a cage for a month and let it heal which it did. A bit crooked but it sure isn't slowing my little guy down. He flaps the wing and still rules the roost.
Once again. I am so sorry.

I wish I was more I could do to help.
I also wanted to add. You have done all you can do to help her. She's had a good and loving family and a good life until now. An old saying goes, when God has his hand on their right shoulder, you may as well remove yours from the left because God always wins. Same goes for chickens. I'm afraid.
PS. Thanks for the tag,
@Wyorp Rock