Use the Silkscreen Image part (for a PCB, use Similar part for Schematic… they are standard fritz parts).
Then, load your SVG into it. The SVG does NOT need layers/etc. I drew the box below in LibreOffice/Draw and saved as .SVG (no fussing!).
Naturally, you can use Dashed lines/etc and draw any shape… (and use most any graphics program to draw it)
ADDED a Schematic view with Box…
