Hi. Our 2nd daughter was placed with us when our oldest daughter was 3.6 (they seem close in age because they are related siblings but they didn't understand this so I guess this didn't have any affect).
It was a real roller coaster. DD1 naturally didn't like being dethroned as the only child and it brought out a lot of anger and upset on her part.
The worst part was when she began attacking her younger sister (which we thought would happen but were unprepared for the frequency and severity). After my husband went back to work after his paternity leave things went downhill.
At the worst point DD2 was being physically attacked by DD1 every couple of minutes. This was made worse by the fact that DD1 is very tall, strong and robust and DD2, as well as being prem is very slight and undersized generally. It was constant and exhausting. The worst point came when DD1 kicked DD2 in the face which propelled her down the stairs.
I found it really hard to keep my cool. I felt angry and hurt by DD1s actions. Although I knew that DD1 was not in control of her actions and was really upset and confused by what she was doing and starting showing signs of experiencing shame.
I felt like I couldn't protect DD2 who had been the oldest child in the foster home and fortunately never had to experience anything like it before.
It got to the point where I couldn't see any way of carrying on and thought "If I can't keep DD2 safe, what happens next?" I dreaded the idea of having to return her to her FC but it kept popping up.
Thankfully we have a fantastic adoption support SW. I phoned her in tears, she came straight over. We discussed strategies in detail (including the use of "parts language" - Holly Van Gulden - which helped DD1 deal with her issues of shame - highly recommend) We got through it.
We are now only 7 weeks in but already it has improved many times over. Everything is calmer and the 2 girls have the odd swipe at each other but it is 50/50 now and feels much more normal.
I am so glad we stuck at it because giving our DD1 the chance to be a sister is such a precious gift. She is really thriving and blossoming before our eyes, I feel like I love her even more now I see her being such a protective , caring, wonderful big sister (I didn't think it would be possible to love her any more)
She WAS unsettled and she really didn't like it at first but she LOVEs being a sister now and it is so lovely to see them together.
DD2 has come on in leaps and bounds and is also thriving. The first 2 words she learnt ahen she came home were "dada" and her sisters name. Cute!!!
I have focussed on the effects on DD1 because that is where you are coming from.
I am so excited for you on your journey. I am sure it will be a fantastic life enhancing experience for all of you.
There is nothing like seeing 2 little dressing gowns warming on the towel rail, or two pairs of wellies by the front door.
Wishing you lots of luck and fun