The person you need to have a stern talk with is yourself. Whatever you say to her will go in one ear and out the other. You don't establish a boundary by proclamation. Instead, you simply start defending against her intrusions. She'll figure it out. I'm sure she's a dear soul 😁, but think of her as a puppy . . . or a toddler who hasn't learned English yet. When she starts pawing you, press her arms back to her side and say, "Sis, we're going to be a little less touchy-feely."

I once watched a pretty nurse speaking with an elderly male patient who was getting ready to "cop a feel." She cupped his elbows in what seemed like a sweet gesture, but it gave her control of his arms and hands. I can't really illustrate that adequately, but you can experiment and find what works. Nurses often deal with patients who want to plant a kiss, or pat a butt. They learn how to deflect those advances, without saying a word. You start to "claim your space and own your space."

Once you change your mindset, you'll figure out ways to stop her intrusiveness - whether physical or otherwise. She'll adapt . . . but she'll keep testing you. Good luck. You can do it.