Answer:
If the drilling holes are subject to a regular grid, they can be defined using built-up cross-sections (see Image 01).
Otherwise, there is still the possibility to reduce the cross-section in "Properties" (see Image 02). This results in a general reduction in the stiffness of the cross-section. Unfortunately, it is not possible to distinguish between the reductions in the compression and tension areas of the cross-section. This option is only available when remodeling the cross-section in the SHAPE‑THIN program or in some modules of the JOINTS family in the area of the connections.