An odd question, but...sling attachments

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All,
I'd like to canvass the membership here and see if any of you have encountered ersatz sling arrangements on German or German-captured rifles with butt stock sling 'dish-outs.' The latter are the areas of the mid butt stock which were opened up to accommodate the use of a side sling arrangement without the use of dedicated hardware and metal attachments. These first saw use on K98 carbines in WWI, but I'm focused on WWII examples.

As background, I bought a G.24(t) a few years back that came with a K98k sling that had lost it's frosch, the part that secures the sling in the dish-out. Without the frosch, the sling can't be secured and will slide out. In this case, the sling was secured by a small metal piece that held the sling in the slot, without compromising function. I later learned that this metal piece was used on pre-war Yugoslavian slings to secure the sling at a particular length. They were paired, but mine only had one. Have any of you seen these or anything similar used on German or German-captured/modified rifles? I'm aware of different side sling arrangements that were used on rifles that originally didn't have them, but I've not seen these small metal pieces used anywhere else. I've attached photos of the piece and how it's currently being used on one of my German-captured Czech VZ-24's.

Thank you,
Pat