Treat an Import DXF like a picture?

I have received some DXF files that were exported from Adobe Illustrator from a Graphics Company I am working with.  Of coarse these skteches are a mess, so I want to sketch in SW from scratch.  I have sucessfully imported the DXF as sketches in SW, some even will extrude without having to retouch the original vector art.

My problem is that the person that made these files was VERY scrolly (lots of splines and radi), but nothing has any real proportions or diminsions.  What I am thinking is that I want to lock the sketch somehow, so that I can create a new sketch "over top" of the original sketch (like a picture) WITHOUT having any relations to the original imported sketch.

Is this possible or is there a method to this madness that I can implement?

Thank you,

Chris

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