Hi tcangel, & thanks for pointing that out Candy - missed it entirely! I think I read 'at a stud in a pen'. Tcangel, if she's in foal, that is relevant to her behaviour, as well as to her - & the foal's - health & wellbeing. Sooner you find out, the sooner you can make plans... one way or another. What sort of horse is she? What is the stud? Does the old owner run a stud farm or...?
Honestly, it sounds like you're quite inexperienced & have taken on an uneducated & inexperienced horse. Therefore there is just way too much to go purely on theory - not to mention all our different opinions on forums to sort through - so if you want to keep the horse, I would strongly suggest you work with a good trainer, or experienced horseperson, for hands-on instruction.
Don't stop learning the theory(ies) either though. Understanding how horses think & the principles behind the training/actions is vital to developing a good strong leadership role.... having fun & staying safe. Learn about horse behaviour & bodylanguage, etc. Learn about the 'laws of learning', or behavioural training principles. a great little easy to read book on that is "Don't Shoot The Dog" by Karen Pryor(not a dog book
For now, until you find a trainer, I'd probably just do stuff with her in the paddock or such, if she's nervous in a stable. Get to know her on easier grounds first, before you start testing the relationship with new & scary experiences. When a horse is frightened, they almost 'can't' think clearly & their whole focus is on self preservation, not the handler. It takes training & being *trusted* leader to calm the horse & get him listening again if 'overfaced'.
Oh & yes, hold onto the reins/lead & keep her head bent slightly towards you & 'listen' to her bodylanguage, be ready to correct & stay safe when she *starts thinking* about kicking or such. Once you develop an understanding with her & she learns that she mustn't 'fob you off' like that, of course, you shouldn't need to tie/restrain her just for handling. Sounds like it's for the best for now tho. I'd keep the kids at a safe distance until you've got a good thing going with her first too.