About Switching References in a Drawing
If a source object being integrated is displayed in a drawing, any drawing references to merged items have to be switched to corresponding references in the target model.
For example, if a hole was added to the source object and the diameter of the hole was displayed on a drawing, the dimension on the drawing has to be switched to reference the hole which has been merged into the target object.
Many references can be switched automatically when items are merged between the source and target parts or assemblies. In some cases, however, references must be switched manually.
For example, in the case of a hole added to the source object, after the hole is merged into the target object, the system must be able to automatically switch the diameter dimension shown on a drawing.
If, however, you redefine the section of a feature in the source object so that it looks completely different than that in the target object, the references might not be readily compatible, and you must switch them manually.