I've just gone on a little bit of a rant about what I'm about to say on another thread so pardon me for repeating myself almost word-for-word, but -
Respect is key. If your horse is being rude and pushy towards you, then she does not respect you. You need to TEACH her some respect. First, you will need to gain it in the round pen, free lunging with LOTS of changes of direction. You change the direction the horse is going, YOU are in control, and the horse will fight you at first but if you stick to your guns she will give in.
I don't like stud chains and IMO if you have to use them there is something very wrong with the partnership. I'd use a chain on an actual stud purely because I'd rather have too much bite than not enough when dealing with stallions (they have a reputation for being dangerous for a reason), but not a mare or a gelding.
What I would do with this horse, AFTER re-inforcing leadership in the round pen, would be to teach it some basic liberty. Backing on command without being touched, especially. This can be taught amazingly easily, and I will explain it if you like.
And then, once you have that liberty backing as soft as possible every time, translate it to the stall. Back the horse away from the door, and get on her case for even a shift of weight forwards without being invited. No creeping allowed either. I know a horse that will suddenly "get an itch" and use that as an excuse to move his foreleg forwards, and then he'll put weight on that foreleg and slowly creep into your space hoping you don't notice.
I am REALLY strict about two things. Dinner time manners, and gates of any kind. My personal space comes a close third, I will not be crowded under any circumstance.
I used to have a gate barger (the horse I had before Monty) and he got himself injured because of it. He got his hip caught on the gate which then pushed him into the gate post and the latch punctured his side. A few millimetres deeper and he'd have punctured his rib cage, maybe even a lung, and I'd have had a dead horse. Ever since, gate manners have been among my top priorities.
Keep that in mind when you get on your mare's case about her rudeness regarding stables. It can end in tears and injury for both horse and handler. She sounds like a pushy type which means you will need to be more pushy and more dominant. Both mine are pushy and in making sure they respect me I have been accused of abusing them before now, but somehow I am the one who rarely has rude horses and I never have a problem catching them - and they are both very affectionate. I think we've gotten far too soft on our horses to be honest. They NEED to be told, stand there, move over there, go at THAT speed. They NEED to be told to get out of the way when they're between you and where you want to be.
I'm not advocating abuse or anything of the sort. I'm just saying, we need to have a good "last resort" that we actually USE. When you're working with a horse, you need to start very soft, because you want them to eventually respond to that initial soft aid that may be almost invisible, or even completely invisible. But you also need to graduate your ask until you're telling the horse, and then demanding, and at last promising it that it WILL do as it's told.
The attitude goes something like this:
"Please, oh pretty please will you back up?" (for me, that's gentle steady pressure on the noseband or bit, but at liberty it can be as simple as a raised finger)
"NO" says the horse, and she doesn't respond. Guaranteed you'll get this the first many times. Don't increase your "ask" phase, you want her to respond to the smallest of aids in time.
"Back up" (I use firm pressure on the noseband or bit, at liberty it can be a wiggled finger or you can go for the rope with a LIGHT wiggle)
"NO" is a possible answer. Probable, if she's gotten away with ignoring you for a long time.
"BACK UP RIGHT NOW" (I use an on-off pressure on the noseband or bit, and at liberty this is where you need your rope and a moderate wiggle)
If the answer is still "NO"...
"YOU WILL BACK UP NOW OR ELSE FACE A PAINFUL AND LINGERING DEATH" - I guarantee you will only have to use THIS phase once or twice if it's a good enough fourth phase. For an effective fourth phase the horse has to honestly believe she's going to die. THIS is where I've been accused of abuse, and if you have to go to this phase, you have to have brilliant timing so that you can stop as soon as the horse offers what you want.
The trick with the fourth phase is to not actually get mad, but make the horse THINK you're mad.
So what do I do in the fourth phase? I'll yank on that lead, whether it's attached to a headcollar or a bit, because that horse is backing up NOW and it's been given plenty of chances to give me the right response with a gentler aid.
And THAT is with a horse that's learning... My two KNOW so I will often go from the ask phase to the demand phase. I haven't used the promise phase in months.
A CLEAN SLATE FOR THE FUTURE