Editing feature line destroys finished surface!

[rezaUYV3V]

If I add, edit or move a feature line in FG surface, this happens....(please see picture)

There is no crossing feature line anywhere, but it adds some low/high points automatically to the surface. Any reason? I've done multiple audits, purge, -purge, and restarted my CAD and PC. Still can't edit any featureline. 

[rezaUYV3V · Accepted solution]

I found the solution lol

Move all the parcel lines to a different site. Never knew that parcel lines are going to interfere with feature lines on the same site.