...that will go unanswered (which is itself an answer that says A LOT)
Let's say in the town where you live, you are involved with a hobby or activity -- say, model trains -- and you are a member of several model train organizations. There's going to be a couple of get-togethers in your town of model train aficionados from all over -- one a sort of convention, the other, a few weeks later, a celebration with an expo for the public. Your local organization is going to participate in both.
Two years after these events, never-before-seen photos made at them surface on the internet. A couple of them show your local chapter's officers posing with a college student who is evidently a model rail fan. He's standing with your officers and some other expo-goers behind a model rail layout, everybody's smiling big. In some of the photos, he is identified as a member of your local group.
Turns out he lives out of state and attends school out of state, and at the time of the convention, he had helped to start on his campus a NAMBLA-like group. He's heavily into promoting and legalizing man-boy love (homosexual pedophilia) and his perception that model training attracts young boys accounts for his interest in it. Since the convention, he has actually made quite a name for himself with that campus undertaking.
Is any of this the fault of your local group's officers? Back during the convention, should they have known he was a homosexual pedophile? Does his posing with your group mean that your group comprises homosexual pedophiles, or at least supports them? Do the photos obligate your group to "disavow" affiliation with such groups, or their beliefs and goals?