creating polygon

[Lacsa]

Hi Folks,
I'm also new to this forum, so please be gentle with me as well.
Can anybody tell me how can I create a polygon wich is not be hided in parts from an originial FS polygon? I already tried to fix it with an exclude file as well as with changing altitudes and also I tried a flatten file and tried different layers - but without result.
Does anybody have an idea?

Many many thanks!
Bob

[Barney]

Try placing a "runway" of sufficient dimensions to cover the intended polygon area, but texture the runway as 'invisible'. Be sure to have the correct elevation for this area in the General Menu as well as the correct coordinates, etc.

Barney