If I'm a designated driver to youths and they are drinking and carrying marijuana in the vehicle I'm driving them in, can I be charged?

If the drugs are in one person's pocket the police will usually just charge that person. If the car smells like pot they may arrest everyone. If the drugs are found in the car everyone can be charged or just the driver if he admits the drugs are his. Never consent to a search or make any admissions or statements, just remain silent and do not let the police manipulate you into giving consent to search or talking about whose drugs they are.