it's only 2 weeks and you can get their school work so they don't fall behind. You can ask your attorney what is the best thing to do. perhaps he can send a strong letter to her attorney who would advise against such a dispicable act. it's going to make her look very craptastic in court. Can the school tell if she was drinking at the time or suspect and they could not let her take kids until police come? (who could administer a sobriety test)?
these are her own children she is choosing to traumatize. You could press charges against the grandmother in the interim? THAT might stop her?