These guys were definitely some kind of group.
Father had a beard and hat. Suspenders where light colored homemade looking cloth. The pants were like a big square flap buttoned on both sides.
maybe Mennonites. Didn’t really want to stare them but the haircuts were very noticeable.
The clothing you describe is definitely Amish. Was there a buggy nearby?
They could have been traveling, and stopped at the station so their van driver could refuel and everyone could use the restroom and purchase snacks too. They hire vans to travel beyond the range of the horses which is usually about 6 miles.