To Replace Folder or Component Definition in Mechanical Structure (AutoCAD Mechanical Toolset)

Click Structure tabManage panelReplace Definition. Find
To replace components, click the component tab. To replace folders, click the folder tab.
In the Replace box, click the arrow on the drop-down list and select the definition of the folder/component to replace.
In the instances list, select the instance to replace. To select more than one instance, press the CTRL key and click the instances.
In the With box, select the replacement component/folder.
Click OK.