@Sharon1794 Any existing bookings will not be affected by the changes you make.
One other thing to consider - Perhaps block the 1 and/or 2 bed listings in high season to force the bigger listing to be booked. Blocking a date in one calendar does NOT block the other calendars even though they are synced to each other. This is also important to remember if you want to close down for a week (or take a private booking) as you will need to block all 3 calendars.