aggressive 8 month old CKCS

Question
We have had our 8 month old King Charles Cavalier since she was 8 weeks old. From day one she was aggressive, biting, growling and attacking our 4 year old cavalier. We have had CKCS for over 25 years always from puppies and never had any behaviour probs. We tried from day 1 to stop the aggression, we praised good behaviour, have loved her and given lots of love and attention. We have 3 8 year old girls who adore her but she has now gone for them for no reason, she tried to bite my mum who was stroking her tummy we think because 1 of her toys was close by. She attacks our other dog just for entering the room, she has now become subdued and  terrified of the pup as are we. I have read the advice on here for treating aggression, but need advice as to whether it is safe for us to try it with all of us being terrified of her. i would never forgive myself if she was to seriously bite one of my children, but they would be distraught if we gave her up. We have no experience of aggressive cavaliers as they are well known for their docile, loving friendly temperaments!!
Do we give up for safety of try to curb this aggression? Any advice gratefully received.!!!

Answer
Aggression is a difficult thing to address via email since there are many causes and much of the solution can depend on an understanding of canine body language.

I suggest you get in touch with a trainer who can come and observe what is going on and give one-on-one suggestions and training advice:
http://www.apdt.co.uk/local_dog_trainers.asp