After a project has been created, you can still import groups from the master schedule.
Select group allows you to select different groups to browse.
Import Entire Group will create a record in the project schedule for each record in the master schedule. Have the option to erase the existing items in the schedule when you import the entire group.
You would want to if you had selected the wrong state for the room definitions. You would not want to if you wanted to add to the schedule, or had made changes to the schedule that you wanted to keep.
Can also import single records. Have the choice to create a new record in the schedule or update the record that is current. If record name already exists and you import new record, it will create it with (Copy X) added to the name.