First off let me apologize for the very poor artwork--I'm a shaky left hander and I free-handed these drawings. I also want to say I am a fan of all things modular. I like to customize my gear to what I am doing. With that being said I designed 2 different variations of the same design. Option A is beltless snap system (you will see what I mean in a second) and Option B is a belt/snap system. The sheath on Option A is tapered. The bottom width of the sheath is 1/2 inch wider than the top. Option B is parallel. I didnt include belt attachment but both would just have a belt loop at the top with a dangler attachment ring on it.
I wanted a pocket sheath for my 14 that would also be a piggyback sheath for my 9--I also think this would be cool if it was interchangable between the other big Beckers (meaning I could take this pocket/piggyback sheath and attach it onto my 2 also). Option A would have the snaps attached directly to the sheaths and pouch so that they could just directly snap together.
OPTION A
The components-Note the snaps on the front of the sheath--they will attach to the snaps on the back of the piggyback/pocket sheath and pouch--they are not to scale---
Back view of the pouch and piggyback/pocket sheath to show snap placement
All snapped together
To get an idea of what it would look like
OPTION B-belt/snap attachment option
For this option the ferro rod sleeve/pocket is dropped and the sheath has eyelets (that can be used for attachment purposes) sticking out beyond the width of the sheath (in a half hexagon sort of shape)--The distance between these eyelets would be the same as the width of the belts used to attach the pocket sheath and pouch. The belt can be sewn directly on to the pouch or could have the snaps in the back (same as option A) and can just attach to the belt in the same manner--pocket sheath would have to definetly attach to the belt in the same way as option A to keep its function as a pocket sheath--belts can be moved/switched around to customize it to your likings--
The components
Can be attached in multiple configurations (EDIT--I forgot to draw the snaps on the belts)
Note that there are 3 places a belt can fit between the eyelets--you could drop the pocket sheath and attach the the pouch in the center spacing--or vice versa ( 2 pouches would be a cool configuration too--not pictured)
Once again I apologize for the bad drawings. I should have had my 5 and 4 yr old sons draw them up for me

--let me know if you have any questions or if I left anything out