Had a question today, regarding components which would override the lineweight of the walls they where placed up against.
1. Open the component (family) in the family editor
2. Locate the build in masking region
3. In the element properties of the masing region, uncheck the "Draw in Foreground" box
4. Hit "OK"
5. Create a new Ref. Plane, just above the Ref. Level, and name it "Mask"
6. Select the masking region, and set it´s work plane to the new "Mask" Ref. Plane
7. Load the component into your project.