You can replace a part instance with an instance of a second part. To be precise, you are replacing the part from which the part instance is created. Abaqus/CAE positions the new part instance such that its origin is located at the origin of the original part instance and their axes align. In addition, you can choose whether the new part instance inherits all the constraints from the instance it replaced.
The replace operation does not change the attributes of the instance. For example, if the original instance is dependent, the instance that replaces it will also be dependent. As a result, if an independent instance of a part exists, you cannot use the replace procedure to create a dependent instance of the same part.
Replacing a part instance is useful when you are replacing a part instance with one that has similar geometry. For example, the new part instance might have additional detail that was not present in the original part instance. You can also replace a geometry-based part with a mesh representation of the same part. For example, you could replace a part with the mesh representation of the deformed part imported from an output database.