my grandaughter was arrested for the 1st time in her life she wasn't doing drugs but the boy she was with had them on him

Since I do not represent your granddaughter, I cannot advise you as to her cases or charges.  However, I will provide you with some general information based on the facts, assuming they are correct, that you submitted.  Unless she pled to or was found guilty at trial of more than one charge in the first case, it would appear that it was a felony charge.  The highest level of a misdemeanor charge only carries up to a maximum probation period of one year.  Therefore, she could only be placed on probation for 18 months if the charge was a felony -- or if there was more than one misdemeanor charge.  Additionally, even if she violates her probation, she could not be sentenced to more than a year in jail on a first degree misdemeanor -- so it would seem she must have been on probation for a felony charge in the first case.  Even if she has no other criminal record, if the court determines that she violated her probation (assuming it was a third degree felony charge), the court could sentence her to prison for up to 5 years.  That does not mean that is what will happen -- but only that legally the court has the power to do that.   Depending on the facts of the second case (and keep in mind the facts as relayed by law enforcement may not match the facts as relayed by your granddaughter), even if she was only charged with a misdemeanor in that case, it could easily be sufficient to violate her probation.  However, also depending on the facts in that case, if law enforcement did not have any legal reason to make a warrantless search of the car she was driving (even if it was not hers) -- and if law enforcement did not get her consent to search the car, there may be grounds for filing a motion to suppress the evidence.  The outcome of such a motion could determine whether the state can proceed with the charge in the new case -- as well as any violation of probation in the original case.  Her attorney should be able to provide legal advice and further explanation as to that.