Ya, I'm not really sure about the "or both" part. For one, under whose control is the spell. It affects the magus, so the familiar must control it. It affects the familiar so the magus must control it. How can they both simultaneously be controlling it?
Why does "control" figure in here? A Group spell that contains the magus affects everybody in the group, including the magus, regardless of who is controlling it, right?
Xavi
It is generally the rule for familiar enchantments... but I made a mistake without by book because that rule applies to affects that only work on one of them, not affects that apply to both.
Chris