Toddler stressing me out

2.5 year old is causing havok ever since we returned home yesterday. We have made her feel so included and she likes touching the baby. But she keeps screeching for things, can’t negotiate anything, doing everything we say not to, not sleeping properly, stealing baby’s breast milk, being too lively and coming close to too many accidents. I’m feeling so stressed with her. Any advice welcomed. Sick of her voice now constantly whinging.

Love her so much though :(