SR 5th ed. Question re: Exotic Weapons

[Orudeon]

I'm giving my players the gift of custom weapons designed from the ground up just for them, but I ran into a problem. How do I make a new sub-type for Exotic Weapons (so it's a valid selection in the drop-down box when you add an exotic weapon in advancements) and how do I make the weapon scale with the custom exotic weapon skill?

I tried making a new exotic weapon skill by making a copy of Exotic Ranged Weapon but that didn't work. it wants me to pick which weapon anyway.

On the weapon end, I tried adding a new "Counts as Exotic Weapon" tag for it, but it scales off Pistols because I thought that's the Skill/Specialty/Range i needed to pick. So not only do I need the new skill to show up in the S/S/R window (I think) but I also need it to show up as a possible advancement AND show up as a "buyable" item that scales with it.