Nick, Can you simply edit the "shape" of the Viewport that you want on the bottom. Select|Edit Node-> Add some nodes as required, then Snap those nodes to the Vertex(es) (and/or Middle, Nearest on Graphic, etc.) of the Viewport that you want on top. That would seem to be the "cleanest" way.
Remember, Viewports do not have to be a simple rectangle. -Alvin
Edit: Sample Screen-Captures Attached Below (Edit #2: Whoops: I got a little hurried and sloppy in my drawing. In the the first two pictures below, I didn't have the bottom Viewport's node that is at the top/left of the top Viewport exactly at the Vertex. I corrected that before creating picture 3. -Alvin)
Edit #3: After re-reading Nick's original post, this Topic, it occurs to me that Nick may be wanting to put the "top", smaller, Viewport within the boundaries of the "lower", larger Viewport. If that is the case, then my method described in this Post, does not work at all. (Edit #4: In the "....-4 .pic below you can see that I had a solution: I added a bunch of nodes to the larger Viewport; Snapped these nodes at all four corner vertices of the smaller, interior rectangular Viewport, closing to itself; made the larger/bottom Viewport line "Invisible"; then added my own rectanglular Polyline (in Black), Snapping to the corners of the larger/bottom Viewport. This process you can see in "Paperspace 1" of the attached .tcw drawing created in ver. 11.2
« Last Edit: September 13, 2012, 11:19:16 AM by Alvin Gregorio »
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V20.2PP(57.0)[as of 3/12/15]; V19DL(54.2); V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)