Change in reservation

My guests booked the upper part of a vacation home and are now requesting to book the entire home but when trying to make the change on owner rez it shows that the unit is blocked since the upper unit was originally booked and block.. Help on how I can change without cancelling reservation.

Please write in to the Helpdesk with specific details so we can take a look.  Normally you should be able to do this.

When changing a booking on a mutually blocked property, you first have to remove the mutual blocking to free up the availability. You can view the webinar linked at the top of this article (the mutually blocked property change is shown around minute 11 or 12):
https://www.ownerrez.com/support/articles/combined-properties-blockoff-lockoff

Then you make the change per the article:
https://www.ownerrez.com/support/articles/move-booking

Once you've made the property change, be sure to re-initiate the mutual blocking!