A friend of mine was telling me that her first daughter was fine with their new baby for a while and then started acting out when she finally realised that the baby wasn't leaving & staying for good. So it might still be because of the new baby.
My dd was doing the same thing recently: delay tactics (newly potty trained), tantrums, crying hysterically and getting out of her bed and room.
Our head-on battle wasn't working only making things worse.
Our bedtime routine:clean teeth, wee, bedtime stories, choose a favorite toy to sleep with, talk about her day & what she's going to do the next day (5mins), hug & kiss, turn off lights & leave the room straight away.
So when it was time for our talk, I told her what I expected of her when its night time and that she needs to sleep, stay in bed, stay in her room until the light comes through the curtain. We had introduced a reward chart so I told her that she gets one sticker closer to her reward if she does it. I reassure her that I'm right downstairs & that I'm very proud of her for being such a big girl.
I also made some ground rules about our routine: maximum 3 stories and 1 toilet run.
I go through the same conversation with her every night. We had one or two middle of the night wakings but I put her back to bed reminding her that it is not morning yet, and leave the room.
Now when she wakes up in the morning and comes out of her room. She would ask me if its morning yet. I would say yes and that I'm very proud of her for waiting till the sun came in before coming out of her room. Then she runs to her dad and tells him what she did and what a big girl she is.
Our successes with dd like moving to a big girl's bed, potty training and sleeping on her own were all achieved through talking to her and reiterating what is expected and positive reenforcement. Hopefully it will work for you too.
