See my answer about splicing in a panel. I have always allowed a splice to make a branch wire longer but not to add a second load or rewire the circuits except as I mention in your post about splicing in panels.
To the original poster, could you be more specific with your query?
You've asked this question twice now, I'm assuming because you didn't like the answer you got the first time.
However, it's too broad of a subject, to give a quick answer. Sometimes it's allowed and sometimes it's not allowed. Other times, although the code says that it's not allowed, we actually are allowed.
