MUST your D vacate the room? No. She pays for half of the room and perfectly within her rights to stay.
WOULD IT BE NICE for her to do so? IMO yes. If she and her roommate get along well, if this is the only time she has been asked all year to leave then I think it would be a very nice gesture for her to spend the weekend in a friend’s room. She certainly can let the roommate know that this is a one time thing and that she will need to stop by during the afternoon to change clothing, get books etc. but they should be able to work that out.