Hi 

I did not look at the extension because I do not have Visual Studio in this machine, but from your description the simplest way is to have an auxiliary eSpace and store all of that data in an entity. I do not know how the library saves biometric data, but most likely you can save it to XML or plain binary data, which you can save as an attribute of an entity...

If you use this approach you can also create black-box approaches to the API by having your users call actions in the eSpace instead of the ones in the Extension.

I do not know if this helps?

Cheers,
Acácio Porta Nova