N.: I can only tell you my experience. I have 3 children, my last two children are 15 mos apart. The mistakes I made and truly regret is that every time my new born son cried I picked him up and fed him or tried to meet his needs. My daugter was very jealous, as any
child would be. She was a beautiful little girl too, but really resented her brother coming along. I think part of it was because we pushed her into growing up too soon. My suggestion is that you don't always rush to the aid of the newborn (it doesn't hurt for them to cry a few minutes- I never wanted to let mine cry much) and let the 23 month old daughter see that you have time alone with just her, and that she is important. Or maybe tell her the baby needs fed now, or changed, or whatever and mommy will play, read or whatever to you in a few minutes (or whenever it is convenient to you). Please just make sure she knows that she is important still and special to you. Often, I think it is so easy to get wrapped up in the baby (especially when they cry), that we can forget (in my case that the 15 mos.. old was still just a baby too).
That's the best thing I can think of to have special time alone with just you and her, and make a big deal of it. I would continue to do this. My husband and I have days out with our three children. One day he will take one out by themselves and spend the day with them, next time another one alone, etc. Then it will be my turn to do the same.
Maybe if you are married (I can't tell my your email) have Dad spend some time alone with just her too.
It sounds to me like there is a lot of competition for attention with the other kids in the mix also. I would also look for things you can praise her about so that your focus is not
always on the negative (which is so easy to do). Maybe say words like I know you want to be nice to your sibling, cousin, etc. I know you are a good girl and that you will do the right thing. Sometimes if you stand over the child it will create a power struggle, but if you say I know you will do the right thing and not hit so and so because you are such a sweet girl, then walk away so she knows trust her to do the right thing.
Another suggestion I have I learned from Growing kids God's way. You don't always have to make her share every toy, it's ok to have some special toys of her own she doesn't have
to share. She can keep them in her room.
One thing that really saved me when my kids were younger was to do room time or blanket time too. I would pick out the toys/books I wanted my kids to play with and
leave them on the blanket with only those toys for a certain amount of time, you have
to work with them on this for awhile. You may start with 15 minutes and do not let
them leave the blanket/room. Eventually they will come to love room time/blanket. My kids really enjoyed it. It gave them time to have their space and think and create. I also
think it teaches them patience and how to be still and be creative with the toys they
are given.
We also would not allow them to play with the children they were hurting. We would put
them in another room/sit on a chair until they said they were ready to come back to the situation and not do any harm.
I hope some of these suggestions help. These are things that helped in our family.
God Bless you, take care,
K.