A0-1193-6, 1962, Friendship 7, Apollo 1 Memorial,  FDC, SC 1193, Tragedy, 4 stamp

Add-on cachet is:

A cachet design added to a cover which was originally uncacheted. An add-on cachet should be identified

by maker and date (mine are stamped on the back with the date) so that it is clear that it is not contemporary with the cover.