Create a separate construction style for corner units
Give corner units their own construction style so they sit alongside your normal cabinet styles.
Construction styles are created per cabinet type.
Normal cabinets and corner units need their own construction styles.
To support corner units, create a new construction style, name it for the base kitchen, set style type to corner (instead of cabinet), and edit the carcass fields: carcass core, carcass external finish, carcass internal finish, carcass visible edge band and carcass invisible edge band.