By 'inferior' plan I am assuming you want it as a background plan that you can trace over to create your 3D model.
If that is the case then I would use the 'Drawing' tool to place it on the plan.
It will be contained in one layer that you can turn on or off easily or you can place it in another storey or a worksheet and use 'Trace and Reference' to show it in the background as a reference image.
You will be able to snap to all the points in the DWG and you can even 'Explode' it into its original layer structure if you really need to.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11
