If the invitation was made after you learned of your stuck friend, you might have declined, saying you have an unscheduled guest you don’t want to burden her with. At that point, and since it’s an open house, your landlord will be happy to invite your friend along.
https://www.washingtonpost.com/advice/2022/01/07/miss-manners-bring-friend-open-house/?utm_source=rss&utm_medium=referral&utm_campaign=wp_lifestyle Miss Manners: Friend said I can’t bring another person to her open house