How about starting with the High Seas Fleet after it was interned at Scapa Flow?
Let's say the crews get repatriated much faster than in the OTL, so the scuttling never happens. Caretakers paid for by Germany and a rotating number of naval officers from the Entente powers end up staying aboard instead.
At Versailles, it's agreed that Germany no longer owns the ships but none of the victorious powers can agree on how to share out the ships. The Treaty goes ahead anyway with the final disposition of the ships left for later. All that is agreed upon is that Germany has to keep paying for the caretaker crews.
Haggling over the share out continues and the Washington Naval Treaty conference occurs on schedule. Now none of the major powers want the ships because they'll count towards their tonnage limits. A few of the small ships, light cruisers, destroyers, and the like, do get shared out to various minor Entente powers, but the capital vessels remain at Scapa.
Four years later, Germany joins the League of Nations and an opportunity presents itself. Obviously, Germany doesn't like paying for the caretaker crews aboard the interned vessels at Scapa, so an effort is made to donate the ships to the League. The excuse is that the League can use the ships for peacekeeping missions. Most members see through the ruse but Germany perseveres. The League finally accepts the "gift" during the final years of the Weimer Republic more as a way to bolster that government than anything else.
The League cuts back on the size of the caretaking crews, not that the ships are still actually seaworthy, and the fleet slowly rusts away until 1939 when Britain seizes and scraps the lot for the war effort.
Pretty far fetched, I know, but the whole idea is pretty implausible despite the actual condition of most of the old USSR's fleet.
Bill