Older siblings

Jessica

I put my 7 month down on the floor, rooms kinda messy but I got a blanket down with just his toys on it, and I don’t mind him exploring, I’m watching him. He pulled a string outa some sweatpants he found in the hamper. Was pretty proud of himself. I owe his dad some new sweats now 😂. My 3 year step daughter keeps coming in the room and every time the baby goes to get up she pushes him down or gets in his way. Every time he gets into something she runs and takes it from him. And every time I explain to her “I put the maybe down to move can you please stop getting in his way.” “I put the baby on the floor to explore, I’ll take something from him if he’s not aloud to have it.” And she keeps doing it. How do y’all deal with older siblings and babies playing together?