How to deal with colored lights at events?

Here's a typical situation where somebody decided to use blue light (from a projector!?) to set the mood on stage. The upper part of the people are illuminated with that light. Low whitish ceiling - so I decide to use that to bounce my flash. As a result I get shadows with a strong yellow tint. Very annoying in the main subjects as the top has a correct colour and the shadowier parts a strong tint.

Is there any reasonable way to post processing that in LightRoom? (Only have PSElements).

P.S. The situation was very common: Taking pictures was not part of the plan. In the aftermath however, the pictures suddenly become very important..... And yes, I am still a beginner - so rip at me softly....

What version LR?
You can try the local adjustment brush. Or use an adjustment layer with a mask in PSE.

Versions: LR4.0 and PSE10
I have the cr2 files from a 60D.

Or you could take the lazy way out and convert to b/w.

In Lightroom the approach could be to set the overall White Balance, then to use a local adjustment brush either to "White Balance correct" selected portions or maybe to dial down Saturation of a particular color, say brush over the purplish skins with a negative saturation for Purple.