So, I've been asked by my girlfriend to do her Dance Studio's end of year photos and the scenario is a pretty basic studio-style shoot. I'm going to be hiring a set of two Bowens Gemini 500's (1x Softbox and 1x Umbrella) with a 3mx6m white Muslin background and 3m stand for the actual shoot.

Given my 600D doesn't have a PC port I'm pretty sure that I'm going to need a pc-hot shoe converter for the Studio Strobes, but I was also hoping to use my two YN-560 speedlights for either fill-flash if needed, or with some gels to change the colour of the background. I was wondering if it would be best to trigger these optically from the studio strobes, or can I get some kind of adapter to enable me to fire everything at once?