How old is this cat? I'm not so sure that she is that wild. It seems to me that living in a bathroom all time would make her very, very very bored! She is feeling trapped and probably very lonely!!! That is why she jumps in your lap. It sounds like she is starving for some attention and some way to release her energy. I think that if she were allowed out and got to spend some time roaming around and maybe some play/bonding time with you then she would settle down. You said that she was used to playing with her siblings. Can you imagine being taken away from all of your play buddies, put into a small room day and night, and then get in trouble when you try to find things to do to entertain yourself because you are all alone?? I'm trying to not sound harsh here but this is just very typical cat behavior...even more so if she is young. She can't constantly live in the bathroom! She needs stimulation, attention, and lots of play time. More than anything she needs to be able to snuggle with you so that you both can bond and learn each others ways. She and Blueberry will eventually work out some kind of arrangement. They
will probably become friends. Sometimes you just have to give them some space and let the situation take care of itself. We had our only cat for three years before the second one came along. Sammy, the only, hid for 3 weeks. He would come out to eat and potty. We tried to help them become friends and eventually they were best of buddies. Now we can bring anything in here and Sammy doesn't care!! Blueberry will eventually adjust if you let them work on it!!!
The biggest piece of advice I have for you is to GET HER OUT OF THE BATHROOM!!!
Sorry, I have wanted to scream that since I first read your post!!
Good luck and don't give up yet. You just brought home a new baby and everybody has to adjust and find their place.