I would recommend that you start suppression with 600 mg of valacyclovir and increase it to 500 twice a day if that is not adequate or you could go to 1000 once a day.
Sometimes, taking these suppressively for a few months does seem to calm things down enough to stop but I see no reason to stop. Maybe get your folks through their lives and illnesses and then think about stopping. The meds are safe and effective.
Terri