Keep watching Maggie...hopefully between the aspirin regiment and a little TLC with booster, she'll be fit and fine.
One worrisome note, and I hate to interject it, but Marek's can have a slow wasting affect with only a slight limp. I've had birds over the years succumb to something I suspicion was a milder form of Marek's. They'll eat, drink, but slowly waste. If the tumor is located in a spot where it mildly interferes with the leg nerves, you have mild limping rather than the traditional one leg forward paralysis. If the bird's system is strong enough, it fights off the original acute infection, but will then slowly waste.
But good news is it appeared painful and aspirin seemed to help vs. weak from nerve damage.
She may have simply not been able to get to the food as quickly as the others with the limping and is thin from that.
I have a rooster who I am pretty sure got caught up in some weed-eater twine who has limped for about a month. He is slowly gaining strength and seems to be doing well. Again, no other symptoms like yours, just an odd limp....not present one day, suddenly severe, then slowly improving. He didn't like to put weight on the foot...would put it down and pick it up again like it hurt. I could never find any broken bone or anything that felt like structural damage so chalked it up to sprain.
Good luck. Hopefully Maggie is well on her way to full recovery. I enjoy my Marans...they are my "gun boats" of the flock...big and stately...with wonderful dark eggs.
LofMc