New baby

Sorry for the long post. Hi everyone. I had another little girl at the beginning of Feb. She’s 6 weeks old tomorrow and my other daughter is 2.5 years. Since coming home with the new baby my toddler has been a nightmare with her behaviour. Literally a loose cannon. Throughout my pregnancy she’s been involved and knew there was a baby in my tummy. Nursery read her books about becoming a big sister etc. She come to appointments and scans with me so she was so involved. She come and met her baby sister in the hospital after she was born. She’s a fabulous big sister and is involved soo much it’s lovely to see. HOWEVER, since the day we arrived home from hospital she’s not slept in her own bed. She goes down ok but wakes and screams the place down until she’s in bed with us. It’s not because she’s interested in what sister is doing, she just goes straight back to sleep. FOMO?? On what I don’t know, bless her. Anyway, he behaviour has been awful towards me and her dad. She randomly lashes out at us. She’s recently started spitting when she don’t get her own way. She point blank refuses to do what she’s told (tidy toys away etc). She will sometimes go up to the Moses basket that’s in the living room a shake it really aggressively when baby is in there or when she isn’t. We have tried all different approaches and it’s so sad that she’s like this. I understand having a new sibling arrive in the family is a massive change for children. But my little girl hasn’t ever been left out. She has more attention than what the baby does because we don’t want her to feel any different. Nursery has said she’s good as gold there, HV hasn’t been much help. All I get told is to ignore her behaviour..ok??? I just don’t know what more I can do. I’ve tried doing firm and fair voice, soft and kind, scream and shout. Ignoring her and nothing seems to be working. She has our attention constantly good and bad times. Don’t know what else I can do. I just want my sweet little girl back that sleeps in her own bed 😂😂