Charming idea - and one of my votes too - as I love the two-sidedness ("invite your friends", "deter your enemies") which is perfectly suited to a door hanger!! And I really like the way you've used your color scheme to illustrate the concept again, very clever in a nice subtle way. One tip for instructions on the printed fabric: I recommend the bottom left hand side as that way people will see them when they look at the swatch view.
The extrovert sheep in this ditsy flock really made me smile, Margreet! I love how you have conveyed the diversity of emotions being experienced by the other sheep by their facial expressions! I see amazement, embarrassment, bemusement, amusement, irritation and resignation on these faces!;-)