I’d say that it might help to have a wb target shot in the various lighting situations you may encounter. What I mean is, usually an event will have a limited set of possible lights (assuming white lights mostly), tungsten, fluorescent, incandescence, in a few different temps. You can shoot a target under the main light sources in your area/event so you can use them as a baseline later on when processing.
It’ll also give you a range of values through which to adjust and mix things to compensate for the mixed scenario the subject may be in. Remember, the diffuser over the lens will only give you a WB for the light hitting the lens, and may not reflect what your subject is seeing cast on them.
Unfortunately, mixed lights are a real pain to balance and still have look natural - especially if they’re way different temps. I ran into this all the damn time shooting real estate. It finally made sense to start buying daylight balanced bulbs and replacing them in the fixtures if I wanted to have them on for shots.
If you’re lucky, you may be able to create two version of your image balanced for each of the discrete lights, and blend them afterwards in GIMP?