(off-camera flash) way to have both radio transmission AND pc cord/old flashes?
I have a Canon 5D Mark IV that I currently use with a ST-E3-RT transmitter to work with three 600-EX-RT flashes in three separate groups. Works great. However, there are occasions in which I could benefit from some additional angles of light. Obviously, I could buy additional 600-EX-RT flashes. BUT, I currently have some older flashes I was curious if I could put back into service. I have one 580 EXII and two 430 EX II that I used to use with an ETTL cord prior to upgrading to radio transmission. Would I be able to use a PC cord between camera and the 580 (while simultaneously using my radio transmission/hotshoe with the 600-EX's?). I understand the PC cord doesn't transmit any ETTL info (which I think means I would just need to set the 580 settings on the flash itself). If so, would the 580 be able to act like a master and trigger a 430? If not, then would I be able to use a splitter and have two PC cords to each of my old flashes?
I realize I could buy a PC cord and try - but figured there may be knowledge out there which would help me (and I also didn't know if I could ruin anything by trying without additional knowledge). thanks!!