I certainly did not mean to imply that Strelow was, in fact, a manufacturing silversmith, merely that he was recorded in Scheffler. That he was working in the early 20th century - by which time silver flatware was produced almost exclusively by large manufacturers - makes it all but certain that he was only a retailer.
But even in the 19th century, many retailers and makers both marked their wares with not only their name but some sort of "city" mark in imitation of the larger guilds. Many of these are recorded, but doubtless many have yet to be identified. (
Weltkunst magazine did a lengthy series on some of these smaller civic marks a few years ago; the
Kröpelin mark in a recent post is a good example.)
I can only imagine that the large Treptow manufacturer you remember is Felisch & Kirchheim (founded in 1873) — certainly the city had no larger — but their trademark was “F” in a circle. Conversely, I found
this site about the Wolgast arms which states that the "griffin and key" abbreviated arms of Wolgast have been known since at least the 1760s (as preserved on a limestone monument from that time). I think the appearance of this exact symbol of Wolgast alongside the name of a known Wolgast dealer is simply too great a coindicence. I agree that Strelow was probably a retailer and not a manufacturer, but I think the marks here are all his.