I have been working on giving her more attention and I rearranged the cat room a bit with different beds, which they seem to like. The howling has gone down somewhat and she spends less time outside the bedroom door.
I checked their vet papers and they are due for their check-ups this month, so I will also talk to the vet. Now, that is going to be a lot of howling. They hate the car. When we moved to this house, it was 45 minutes of three cats (at that time) howling. I even put on some Cat Stevens for them to listen to.