The tack I am using came with them and is the same as the previous owner has been using on them for years. I did watch her tack them up and they showed the same behaviours but not quite to this extreme. They will run from you if they even see you coming into the field with a lead rope.
Just because they put up with the saddle doesn't mean it's comfortable - horses are stoic. Perhaps the act of being saddled has been painful long term. Hope not for you because it will be hard to change that association even ensuring a comfortable saddle etc.
But part of it is likely you being new to them - theyre probably thinking who are you to come take them out of their life of leisure & do stuff to them. And sounds like they're still a bit stressed about the move, haven't settled in with the rest yet. Give it time for them to learn to relax & enjoy being there, enjoy your company, get to know you.
I also would avoid separating them for now, wait till they've settled.
Good diet & well balanced nutrition, with attention to adequate magnesium (in times of stress they use more) will also help them settle & relax.
Whether with food treats, scratchies, whatever, if they start associating you with Good Stuff, that's great! Just be careful not to reward 'rude' or wrong behaviour.
Maybe theyre running from you just that it's all new, they're unsure about you or maybe they've always associated being caught, a person approaching with halter & lead as a Bad Thing. I'd definitely be working on changing that. Start by going out with the lead just to give them a treat or scratch & NOT 'catch' them & go gradually from there. Pretty soon you should be able to get them coming - to be haltered - when called.
In my (admittedly limited) experience, there are very few horses that can do this. Most horses need a lot of repetition or they get skittish and you have to start over every time. They tend to do best when ridden frequently, even daily.
I have not found this to be true as a rule myself. IME the vast majority - assuming they are confident with their rider, are experienced enough - can/should indeed be fine going out sporadically. There's something up if not - maybe confidence in rider, maybe training, previous associations, whatever. That said, these girls are new to op & been unworked for years, so I'd expect to have to 'start again' in some respects, regardless how well trained they were in the past. If they were, it 'should' go smoothly & quickly to get them back up to par tho.