I was.
An announcement was made during the noon meal, before the family was dismissed.
Gerrit Lösch read the announcement from Bethel Office informing the family that such a concert would be heald near, or in between, the buildings of the Brooklyn Bethel Complex and that all in the family should be aware of the nature of the complex. In the announcement, or in an off the cuff addendum Lösch mentioned that K.I.S.S. stood for Knights In Satan's Service. I am not sure, don't really remember, if more was explained, or if the announcement explicity said that no member of the family should be caught attending.
An explicit cautionary announcement "discouraging" the family from attending an event was, however, made in regards to a Woodstock anniversary concert close to Wallkill.