You have given her a good name and you don’t need to change that.
It could very well be a jealousy issue due to the birth of her brother. She may need extra love and care.
Make sure meal time and sleep time regulated especially sleeping early at night as it is very recommended in our traditions.
Pay daily charity for their well-being.
Make sure there is no screaming and shouting in the house as it invites devils and repels angels according to our narrations.
Recite athan and Quran loudly in the house.
Before they sleep recite the following for them and if you can hold your hand on their head while reciting it do so:
3 times Fateha
3 times Ikhlas
3 times Ayatul Kursi
1 time Falaq
1 time Nas
7 times Qadr