What should I ask my college when the remote-exam room rules don't fit my shared bedroom?

The exam checklist says nobody else may be in the room for the two-hour sitting. My desk is in the bedroom I share with my sister. She can leave briefly, but she also studies there and doesn't have another quiet place to spend the whole afternoon.

I chose the distance course knowing exams were online. I didn't understand that this sitting would require an empty room for that long. The exam is next month, so there is still time to ask. The library has small rooms, but I haven't checked whether their computers or booking limits would meet the college's requirements.

How do I raise this with the exam office without asking my sister to solve it by disappearing? I want an approved arrangement, not a camera angle that hides the fact that someone else is present.