nothingcomestonothing I am so sorry.
I agree with Devora if you finalise the adoption you will be left to your own devices (my words!).
You said "... so accessing their parents groups is practically difficult and I'm not eligible for any in the LA I live in." Could I ask if your placing authority and the authority you live in could come to some sort of agreement whereby your local authority could provide services or counselling and it be paid for by the placing council? If the placing council provide counselling etc would they provide transport to it. Could you ask for that? The additional cost of providing transport might make them more willing to come to an arrangement with your local authority. Remember to remind them (I am sorry to say this) that your local authority will be picking up the pieces and 'paying' in a few years once 'responsibility' moves to them (is it after two years or three?).
I agree with mrssprout that some social workers may well deal with the loudest people first. If you are so stressed you are emailing and calling all the time and sending calls with 'I will ring in a few days for an update' then that person may well think 'ok let's deal with nothingcomestonothing because then they will be sorted. Do your children still have a social worker? Do they have the same one? My ds is still looked after and he has a social worker and so do we, so there are two people we can turn to if we need to. Is it the same for you?
I think with kids it is important to try and think, where will this go. If I leave this situation, what will happen. Will it get better, stay the same or get worse, how much worse? Situations rarely stay the same (IMHO) some problems just get better, this one does not sound like it will. So how can you get the help you need. Keep a diary of incidents for both ds and dd and if you see the incidences increasing in frequency and severity/stress for you/stress for kids etc then you can tell social services exactly what is happening.
If these things are occurring every few days you can explain the new incidents and explain that this is a new incident, then recap, so as well as this that and the other, now I have this to deal with. But I would actually rephrase it as so now dd and ds have this happening etc so that social services know it is not just you 'suffering' (maybe they feel you are in some ways 'expendable'! But your dd is suffering and is making ds suffer. It is all understandable, their early life maybe made it inevitable . But it may well be changeable, with help [smile.
Anyway, what do I know I am new to all this but I can hear your voice and there is an element of panic, your dd is getting bigger, you have said
She 'tried to break her window with a broom in a temper' (what could have happened if she had done it, could she have been cut, or you or ds or could someone have fallen out of the window!
She '...punches pinches pulls hair etc.' (Yes, all kids might do this, but maybe she does it more, more violently, or maybe you just know she is communicating unresolved distress through this, she is effectively saying , 'help me'.
'She has to win and be first at absolutely everything - will literally push DS down the stairs to get up them first' (that could result in an injury for him, or even for her or both of them!).
If the SW has said '... they won't fund any therapy now ... but she will probably need it 'later'' that sounds like palming you off, is there a medical/therapeutic reason for waiting? Can you find any case studies where waiting was disastrous and threaten them with these?
If CAMHS declined to work with your DD as she didn't meet their threshold - was this a long time in the past, was that before the incidents you mentioned above?
Please do get a local MP or someone who has some power on your side, while you have some degree of time, before you have to go back to work and get that person to work for you. Your local MP should. Adoption is a hot topic with politicians at the moment, it is a lot in the media and it only understandable that you need help.
I sense that you are minimising the problems (no criticism, I think we all do this). It is just that you started with the cat litter tray and then revealed the violence. I think this is a natural protection thing for all of us (to minimise), we want to believe the best of our kids and not to admit to how bad things can be. I felt the same with my dd when she was being very difficult. BUT I feel minimising now will be your enemy, you need all the help you can get now so you will hopefully need less help later.
You must get help. You must convey all this to the placing authority. It is your own decision whether you want to make it sound like the placement may be in jeopardy if you do not get help. Your call. I cannot say what they would do either way. It may be gamble. But will you cope if you do not get help? If there is any doubt in your mind then you need to get that help, and show you can do the job, you can be strong, but you need professional help. (And please do go to GP about IBS, mine was worse and I singled out a couple of fruits and cut them down/out and it has been better BUT I know IBS is vary varied).
If I were in your boat, I would be making someone at the placing authority's life a misery until I got help. Frequent calls, frequent examples of the behaviour and another call to CAMHS.
Good luck. SORRY this is such a long reply!
Please do update us.