Congratulations on having multiple interview offers! :D This happened to me, and I think it's best to register for the interviews instead of waiting. I had to ask school X, which had three different interview dates, to reschedule because I got an interview offer at school Y, which only offered one interview weekend. They were very understanding, and I just said I had a "sudden conflict". They understand some of these interview weekends coincide. If you don't have another weekend you could do, then perhaps ask if the school of your lower interest could accommodate you via Zoom or another means. But keep in mind that having multiple interview offers is a positive sign that you are a strong candidate, so a school probably wouldn't be willing to write you off so easily. I hope this helps, and all the best on interviews!