Oooooo... your Ritter type is the rarest of the bunch. It's the type with the huge cup. Hold onto that one closely.
I don't think the Germans ever had a use for the D-Rings. At least I've never seen anything attached to them in the hundreds of photos I've looked at. The purpose of them was for clipping a backback onto them. This is something the Swiss did, but the Germans apparently never got around to it before the uniform was discontinued (1956-1957 is a small window!). The Swiss, Germans, Belgians, Spanish, and French all used uniforms based on this design first conceived in 1953/54 by the French. It was intended to be used as a standard Europe wide uniform for the European Defense Community (EVG - Europäschen Vereidigungs Gemeinschaft).
As for the British type, I'm not really sure if there is a carrier. I've got one tiny picture from a collector and it's unclear if he rigged up some standard BW straps to hold it together. I suspect that's what he did. In any case, any use of the British type was likely a stopgap measure during expansion rather than something they fully intended on using. Likewise, I have pics of one BGS type leather carrier with a BW eagle stamp on it. This was likely in the very, very early days of the BW when the first members were moved over from the BGS and equipment was in short supply so they repurposed BGS equipment (canteens are documented).
I don't believe I've seen the longer spade carrier before! My guess is they had a bunch of surplus shovels lying about and made some covers to fit.