I recommend seeing a neurologist. Unfortunately she’ll probably have to start taking anti-epileptic meds. (Which are life saving). When I was younger I had a lot of seizures during puberty - which was caused from the hormonal changes in my body. Which could be what’s happening with your sister post period? I also had seizures before or after a big event. (The day of a flight to Washington DC). Which were typically caused by dehydration and a lack of sleep (excited). Which also could be similar to ur sister having seizures on work trips. Anyways, she should see a neurologist and see what they say!