Hi
There are two ways to do this, the fist is how you are doing it by placing the underlay directly into the assembly. This works, the translation and moving can be performed with constraints.
The other is by placing the underlay into a part, and then placing the part into an assembly. This is in my opinion the preferred method as you have a lot more control and options available to you with the underlay. For example being able to add work geometry and sketches. You can also constrain items to the underlay a lot easier.
There is still the issue of the underlay being too far from zero, for me personally, I don't even bother with translate, I just move the dwg file to zero in AutoCAD. I also do basic layer control and line style formatting in AutoCAD, it's just easier this way.
See two small screen grab examples, the part and the resultant assembly.


Reg
2026.3