Use Unify Surfaces to combine surfaces that were previously divided, and that belong to the same body or quilt. You select one target surface. The attributes of the target surface are retained in the Unify Surfaces feature. You can select multiple surfaces to unify with the target surface.

Unify Surfaces is different from Merge, because Unify Surfaces combines surfaces, whereas Merge combines entire quilts.

Watch a video that shows use cases working with Unify Surfaces in Creo:

Divide Surface Part 2: Divide Surface, Unify Surfaces, and Separate Surface Region