Active manufacturing assemblies are assemblies that have been designated for use during a specific Process Plan Explorer session. A process plan can have multiple assemblies associated with it, and therefore numerous related parts. Designating an assembly or assemblies as active, ensures that only the related parts in those assemblies can be used for part allocation during that session of the Process Plan Explorer. This reduces the number of related parts that are displayed during that Process Plan Explorer session making it easier to find and allocate the necessary parts.