Hi all, I need some advice if anyone can help me!

We have a six month old Jack Russel and recently got his little half sister who is 7 weeks old. we have come accross a few problems:

1) Our older pup has stopped letting us know when he wants to go out and just wee's everywhere.

2) Play time together is near non existent as soon as they start playing they both get too rough and the 7 week old is really vicious towards the older one.

I cant leave them both together without the little one being put in a cage incase they fight and something serious happens. But if she is left in the cage then she howls and barks really bad and the neighbours have started banging on walls etc.

My partner thinks that we should get rid of her as it isnt fair on the older pup who has turned out really well and com along way from when we got him 4 months ago. How long do you think is long enough to try and keep her to see if they should settle?

Any help or advice would be greatly appreciated, we only bought the new one as company for her brother when we are out at work.

Mike