Multiple OS with multiple printer drivers

The only alternative I see is to repackage them so that the wrapper-installer picks the correct OS-specific-installer as a postinstall script.
Creating a package like this is not necessarily hard, but it does employ some more advanced concepts. If you're not familiar with repackaging, I'd say your approach is the way to go.

@mscottblake so you're saying i can upload a printer from an Yosemite system, and in a policy, if the mac is running El Capitan I can install the El Capitan driver.

what i can do is in the have a script that checks the OS Version and depending on the version it will call the particular Custom Event for that driver OS X version.

I will just need to create an additional custom event for the El Capitan Sharp driver.

i have the drivers install before the printer gets added.

@tcandela What I think @mscottblake is suggesting putting both drivers in a Composer pkg that places them in a temp location and then in Composer adding a post install script that detects the OS and runs the appropriate installer.

The other way is as you have suggested is to have three policies.
Two driver policies with seperate custom event flags.
Then a thrid detection policy that calls the appropriate driver policy by it's custom event.

You could also kind of combine the two by having one policy the put both driver packages in a temp location and then runs a script from within the policy to install the correct one from the temp location, this has the advantage of being a single policy while letting you modify the script without having to repackage i.e.when 10.12 needs yet another driver :).