my app is a winform app written in VB. im in the process now of working out my issues with sessions and entity managers, but there is a larger problem on the horizon that will screw me up pretty soon.

my app has a core data model. that core will not change, but we are also adding the ability to write plugins for the app. those plugins may add a field to an existing core table or it may add new tables all together. how would i implement this in nhibernate?

for an example, i can have the following table in the app core

user
field-uname
field-pass

the core would have that mapped to an object. but then someone may write a plugin that adds the field last login to the user table. can that plugin just have an object called say custom_user that extends user with the additional fields mapped in an xml and compiled into the plugin dll and from within custom_user be able to access the uname and pass?

if not can someone point me to a tutorial or something that would show me how to fix this. this is going to be a show stopper soon for me.

any ideas here?