I often operate on shows and productions with 8-10 Wireless in play. Good planning and coordination is key in making sure these productions go off without any issues. I employ 2 programs to help me with this FREQ FINDER which is an IOS or Android based app that allows you to input your devices and frequency blocks it then looks at the FCC Database of what is in the area and recommends your best frequencies it works very well. Obviously you should always scan on location to make sure that your frequencies are good.
For more in depth needs I use the PC based program IAS by Professional Wireless it provides alot more features but I only break it out for very large jobs as Freq Finder does a great job. I had IAS before Freq Finder was available.
Lectrosonics will also help you do an coordination as well if needed. The most important thing to do though is SCAN at every location to make sure your day goes smoothly.