Here's the new Master Plan
1. Lay two holsters together and remove the inside loops.
2. Insert a fuel bottle into each holster. Join together with one of the straps that had been disconnected. Leave some play for final adjustment.
3. My dog said I was complicating things:
Attach the bike side of the Bottle Holsters to the bike's rack.
4. Attach the outside loops to the rectangular strap ring.
5. Snug everything up, bury the loose ends. Done.
Any comments, suggestions, ideas, options are most welcome.