Are these littles ever going to get the concept of boundaries?

They've struggled with it ever since we've had them and we've worked on it and worked on it and worked on it and it frustrates me to no end. They sit on top of each other all the time, they think to talk to the baby they need to be on her play mat with her or 1/2 an inch from her face. We've done the whole "if you can hold your arms out and touch someone you're too close" thing...they take it to exaggeration and then go right back to being too close. They play with Melina and shake her toys at her and because they're too close she gets hit in the face or the head and it's just frustrating. I know they don't mean to hurt her, I just wish she didn't have to get hurt sometimes. She loves them to pieces. I know some of it may be their sensory issues too. I'm going to get 3 carpet squares I think today and try that since none of the other rules or ways I've tried to teach them seems to work.

Josiah's getting hurt at school 3-4 times a week too because he gets too close, spins and jumps all of the time and is always bumping into someone and hurting his nose on the back of someone elses head. Iwould have thought natural consequences would have taught him easily enough by now, but no such luck.