Allied Detachments do not have access to the 'Expanded Army List Profiles:' option, and so can't access Exemplary Battle & Legacy Units like the Crusade Force and Mortalis Assault Force can.
When you create a roster you need to add both the main and any supplementary detachments in the same force.
The legacy and exemplary units selection will carry over.
Allied Detachments do not have access to the 'Expanded Army List Profiles:' option, and so can't access Exemplary Battle & Legacy Units like the Crusade Force and Mortalis Assault Force can.