Using "Options and Variants" in Windchill enables the possibility generate Variant part structures from Configurable parts structures.
It is possible to configure Windchill to copy PartUsage IBAs from the Configurable Structure to the Variant Structure in this process.
The system also reuses Variant Structures that exist if they match the requested Variant Structure.
The comparison used to find a matching Variant does not include PartUsage IBAs.
Due to this changes to PartUsage IBAs in the Configurable Structure are not considered when generation new Variant Structures.
The result of this will be that a Variant Structure with different PartUsage IBA values then the Configurable Structure can still be linked to it as a viable variant.