I came up with this script for them:
// DLCR-Sit Right Script for NWN2-Placeables
// Source: German Script Collection
// Adjusted by Black Rider Oct. 2010
void main()
{
object oPC = GetLastUsedBy();
object oChair = OBJECT_SELF;
object oInvisChair = GetLocalObject(OBJECT_SELF, "InvisChair");
if(!GetIsObjectValid(GetSittingCreature(oChair)))
{
object oArea = GetArea(oChair);
vector vLocChair = GetPosition(oChair);
vLocChair.z = vLocChair.z + 0.05; // Correcting hight
float fOrient = GetFacing(oChair);
location locInvisChair = Location(oArea, vLocChair, fOrient);
oInvisChair = CreateObject(OBJECT_TYPE_PLACEABLE, "plc_invisobj", locInvisChair);
SetLocalObject(OBJECT_SELF, "InvisChair", oInvisChair);
AssignCommand(oPC, ActionSit(oInvisChair));
}
}
See, if that does it (I hope, I caught the right one...)