At the bar. You can have witnesses there that your son was forced to drink by his boss and ended up to get drunk. All you have to do is to call a lawyer to defend him.
Don't call a cheap DUI lawyer. I've heard that some cheap lawyers will do the worst job. You can call your last lawyer to help you since he's a good lawyer. Or look for an expert one.
She needs to settle it first before she move. Well, if that DUI lawyer is really interested about your girlfriend's case, then he should come to her and do the possible solutions right away.