Amon_PRC8/_module/nss/spawn_sit.nss

void main()
{
                object oChair = GetNearestObjectByTag ("X2_PLC_CHAIRMIND", OBJECT_SELF, 0);
                if (GetIsObjectValid(oChair) && !GetIsObjectValid (GetSittingCreature (oChair)))
                {
                        AssignCommand (OBJECT_SELF, ActionSit (oChair));
                }
}