When creating or modifying a detail component family, you can use masking regions to obscure lines in different views.
Detail panel
Subcategory panel, and select a boundary line style from the Detail Items drop-down. Masking region sketches must be closed loops.
For a sample detail family with a masking region applied, open the Nominal Cut Lumber-Section family, which resides in the following location:
%ALLUSERSPROFILE%\Autodesk\<product name and release>\Libraries\<language and locale>\Detail Items\Div 06 - Wood and Plastic\06110 - Wood Framing
After you add a masking region, you can sort the draw order.