If you need stuff from Pepakura to move in Corel or elsewhere and be colored, export it in dxf and then just simply draw raw contoured forms, cubes, outlines etc. of the detail.
Or keep importing pdo files with separately unrolled details one by one in to the master PDO file.That would also prevent from teared apart surfaces of the 3D model (edges that can not be joined) if trying to bring it all at once in Pepa.
But I know and can say that working with dxf from Pepa in Corel can be, way much preferable then to use only Pepakura only for such like things.
And some comparison of the PDO tools in SVG and dxf with outlined method. Feel the difference and note the proportion distortions with SVG:
