Is pulling mobs off a bard kite of more than 4 mobs allowed?

[Grunthos]

We have a guild member ask and I have been searching the forums all morning for some kind of official ruling on this other than You may not steal kills.

I have found lots of posts referring to a GM ruling that it is OK if they have more than 4 mobs - but I cannot find an official rule or post on the topic. I am hoping someone with better search skills than I might be able to provide a link to the formal ruling?

Thanks!