Mixing e-ttl2 and Manual Flash

Quick question...

If I mix my 580 exII set on ettl2 and used as the key light, with a couple of cheap slave flashes for kicker/background lights set on manual, will the ettl2 flash adjust its output for the manual flashes going off at the same time?

No. The eTTL flash will have no knowledge of these lights existing. eTTL works by measuring the pre-flash being reflected off the subject. Your manual flashes do not pre-flash. You might make this work if the manual flashes do not hit your subject. If they do hit the subject, they will most certainly overexpose the scene.

Set bg/kicker in manual mode and use key in eTTL if you so desire. Why any issues? Not know why you want to use your key in eTTL mode, why not simple manual for it also.

Okay. Thanks. I'll set everything to manual.