Thank you for contacting us regarding Front Panel Designer.
You can indeed combine simple shapes to make complex hole cutouts just as you say. Simply lay out the shapes on top of each other the way you need them, select them all (shift+left click each, or left click and draw a dashed box around them all), then group them together.
If this group is something you will use repeatedly, you can left click on the group and save it as a named macro file for use later.
Additionally, if you have third party CAD or graphics software, you can draw the shape you need as a DXF, then import it using the Insert -> Free Contour function built into the software.
If you need any assistance creating a custom shape, feel free to e-mail us for assistance.