ooh, come back to read this thread again and have noticed this peach from the dearly departed OP...
I can imagine suddenly having 2 children is a massive shock to the system.
You might be able to imagine what having 2 birth children suddenly like, but you have absolutely no inkling what it's like suddenly having 2 adopted children who;
Are competing... not vying, literally competing for your attention because if they don't get it, they have deep rooted concerns that serious harm will come to them (after all, a succession of adults have harmed them in the past).
This means they absolutely no not differenciate between good and bad attention. Any attention helps calm this terror that they are going to be left, underfed, unclothed. They are in a survival situation and it is like they are drowning.
They are likely not to be able to sleep, for hours and hours on end, leading to exhaustion. They don't sleep during the day either. When they are awake, they may be completely unstressed on the surface. One of mine used to sit up in bed loudly playing with her teddies for hours, not caring one jot if she woke the rest of the house up, which she did, several times a week. NOTHING worked in terms of trying to stop this. It went on for months (she was 6 years old, not a toddler).
They are highly likely to use food as a weapon. It's the one thing they can control easily
You are advised for the first weeks not to go anywhere or meet anyone else, to try to kick start the attachment process.
Nothing holds their attention for longer than about 30 seconds. Nothing. Except maybe TV. Which you are advised to avoid for the first few weeks and months. You cannot leave them alone for so much as a minute as it's likely to kick off.
So, you spend your first few weeks isolated, with two kids who can't concentrate, who are likely to fight, argue, may well even hurt each other in order to paint themselves as 'the good one' and get attention. They more than likely don't mind being the bad one either. If you're shouting at them, you're acknowledging them. Better that in their confused minds than ignoring them and letting them starve.
They will deliberately test boundaries. You will ask them to do something and they will look at you and so the opposite. (Hands up all you birth parents who are thinking 'all kids do that?' Of course they do. But do they do it 80-90% of the time, in a deliberate attempt to get you to lose their temper because a life of chaos is all they've known and is where they, paradoxically, feel safe?)
Added into this, they may well talk about their previous foster careers, and birth family, generally in a way that hurts. I miss Mummy X (often when you are trying to set boundaries).
They can tell you they hate you. And do. A lot.
Then, when you introduce them to your friends, they will turn on the charm. They will behave perfectly. Your friends will start to doubt you when you explain what it's like behind closed doors.
Then, after about 6 months the 'honeymoon phase' ends, the kids start to think maybe this placement is a long term thing. Then the 'fun' really starts.
But yeah... you can imagine what's it's like. 