The late Colonel Applegate might have had some relationship with the Topperweins (I not sure but my father-in-law, who was close friends with him, told me that he didn't think so and, in fact, he wasn't sure if the two had even met) but I believe the Exhibition (Trick) Shooter that he was related to was his Uncle, Gus Peret.
Peret was an amazingly talented man who sadly, never seems to make any of those "lists" we see from time-to-time about such historical performers. Maybe that's the price you pay for shooting for Peters and not Winchester!
The Colonel told me a bit about Peret over the years but he told my father-in-law a lot more regarding things like that, as they were always "visiting" in one way or another; trading stories and exploring new ideas and techniques.
"Uncle Gus" was Applegate's primary influence and pretty much his sole "instructor" (although "instructor" might be too formal a word when it comes to familial-oriented learning) for shooting (especially non-traditional and non-military-related shooting) until he came under the spell of equally famed "gun man" William Fairbairn (ultimately a Colonel himself), from whom he learned and derived a lot.
Colonel Applegate was an amazing man who never stopped learning or thinking and who, contrary to things I've seen written by people who didn't know him, never lived in the past. I treasured our friendship. I learned a lot from him and it was always great catching up with him; either in person or on the phone. He was always willing to answer any of my usually dumb questions and he spoke of things (even grizzly things) with the intelligence and the detachment of a skilled technician but also with the wonderment and the excitement of a man just a fraction of his age.
Lately, as I seem to be growing older by the minute, I can only hope that I do as well in the years ahead.
I hope you two gentlemen do not find my correction insulting but I just thought you might find this of interest. Have a good rest of the week.