If you've done this in ACAD, maybe you'll be able to improve on this method. Sylvia
Example :
Draw a square
Click Hatch
Click Specify Entities
Select the boundary
Enter
Ok
Draw diagonal line to create a small triangle across the corner
Click Edit Hatch
Click inside of small triangle
Click the Rebuild Boundary button
In Command line "R"
In Command line "Y"
Click Specify Points
Click points around the perimeter of the small triangle and once in the interior
Click Enter
Click OK