Unfortunately, you currently can’t assign EPDs to a specific subcategory. You could add an EPD into a template which has additional elements in the specific subcategory (usually you’ll also need to add extra inputs relating to transportation/on-site assembly/installation impacts or materials like fixtures or adhesives which normally aren’t included in the EPDs) however the EPD entries themselves can not be allocated into specific subcategories.
If your concern may be related to BREEAM’s categorisation requirements, BRE currently does not accept EPDs when conducting a study with the IMPACT dataset, so this might not be a problem after all. However I can see where it would be beneficial for users to understand in detail where the EPDs are affecting the study. Please consider making a feature request on our support site so that we may add it to our list of upgrades to the software.
Hope that helps!